diff --git a/problem4j-spring-web/src/main/java/io/github/problem4j/spring/web/resolver/HttpMessageNotReadableProblemResolver.java b/problem4j-spring-web/src/main/java/io/github/problem4j/spring/web/resolver/HttpMessageNotReadableProblemResolver.java
index 5fa0378d..834eb11e 100644
--- a/problem4j-spring-web/src/main/java/io/github/problem4j/spring/web/resolver/HttpMessageNotReadableProblemResolver.java
+++ b/problem4j-spring-web/src/main/java/io/github/problem4j/spring/web/resolver/HttpMessageNotReadableProblemResolver.java
@@ -48,7 +48,7 @@
  */
 public class HttpMessageNotReadableProblemResolver extends AbstractProblemResolver {
 
-  private final TypeNameMapper typeNameMapper;
+  private final JacksonErrorHelper jacksonErrorHelper;
 
   /** Creates a new {@link HttpMessageNotReadableProblemResolver} with default problem format. */
   public HttpMessageNotReadableProblemResolver() {
@@ -74,7 +74,7 @@ public HttpMessageNotReadableProblemResolver(ProblemFormat problemFormat) {
   public HttpMessageNotReadableProblemResolver(
       ProblemFormat problemFormat, TypeNameMapper typeNameMapper) {
     super(HttpMessageNotReadableException.class, problemFormat);
-    this.typeNameMapper = typeNameMapper;
+    this.jacksonErrorHelper = new JacksonErrorHelper(problemFormat, typeNameMapper);
   }
 
   /**
@@ -92,7 +92,7 @@ public HttpMessageNotReadableProblemResolver(
   public ProblemBuilder resolveBuilder(
       ProblemContext context, Exception ex, HttpHeaders headers, HttpStatusCode status) {
     if (ex.getCause() instanceof MismatchedInputException e) {
-      return JacksonErrorHelper.resolveMismatchedInput(e, typeNameMapper);
+      return jacksonErrorHelper.resolveMismatchedInput(e);
     }
     return Problem.builder().status(HttpStatus.BAD_REQUEST.value());
   }
diff --git a/problem4j-spring-web/src/main/java/io/github/problem4j/spring/web/resolver/JacksonErrorHelper.java b/problem4j-spring-web/src/main/java/io/github/problem4j/spring/web/resolver/JacksonErrorHelper.java
index 0099e62a..f48c078a 100644
--- a/problem4j-spring-web/src/main/java/io/github/problem4j/spring/web/resolver/JacksonErrorHelper.java
+++ b/problem4j-spring-web/src/main/java/io/github/problem4j/spring/web/resolver/JacksonErrorHelper.java
@@ -29,16 +29,28 @@
 import com.fasterxml.jackson.databind.exc.MismatchedInputException;
 import io.github.problem4j.core.Problem;
 import io.github.problem4j.core.ProblemBuilder;
+import io.github.problem4j.spring.web.ProblemFormat;
 import io.github.problem4j.spring.web.TypeNameMapper;
 import java.util.Optional;
 import java.util.stream.Collectors;
 import org.springframework.http.HttpStatus;
 import org.springframework.util.StringUtils;
 
+/**
+ * Utility for Jackson exceptions used in situations where these exceptions are the {@code cause} of
+ * the exception that is being resolved.
+ */
 final class JacksonErrorHelper {
 
-  static ProblemBuilder resolveMismatchedInput(
-      MismatchedInputException e, TypeNameMapper typeNameMapper) {
+  private final ProblemFormat problemFormat;
+  private final TypeNameMapper typeNameMapper;
+
+  JacksonErrorHelper(ProblemFormat problemFormat, TypeNameMapper typeNameMapper) {
+    this.problemFormat = problemFormat;
+    this.typeNameMapper = typeNameMapper;
+  }
+
+  ProblemBuilder resolveMismatchedInput(MismatchedInputException e) {
     Optional<String> optionalProperty = resolvePropertyPath(e);
 
     ProblemBuilder builder = Problem.builder().status(HttpStatus.BAD_REQUEST.value());
@@ -47,7 +59,7 @@ static ProblemBuilder resolveMismatchedInput(
         property -> {
           String kind = typeNameMapper.map(e.getTargetType()).orElse(null);
 
-          builder.detail(TYPE_MISMATCH_DETAIL);
+          builder.detail(problemFormat.formatDetail(TYPE_MISMATCH_DETAIL));
           builder.extension(PROPERTY_EXTENSION, property);
           builder.extension(KIND_EXTENSION, kind);
         });
@@ -55,7 +67,7 @@ static ProblemBuilder resolveMismatchedInput(
     return builder;
   }
 
-  private static Optional<String> resolvePropertyPath(MismatchedInputException e) {
+  private Optional<String> resolvePropertyPath(MismatchedInputException e) {
     String property =
         e.getPath().stream()
             .map(JsonMappingException.Reference::getFieldName)
@@ -64,6 +76,4 @@ private static Optional<String> resolvePropertyPath(MismatchedInputException e)
 
     return StringUtils.hasLength(property) ? Optional.of(property) : Optional.empty();
   }
-
-  private JacksonErrorHelper() {}
 }
diff --git a/problem4j-spring-web/src/main/java/io/github/problem4j/spring/web/resolver/ServerWebInputProblemResolver.java b/problem4j-spring-web/src/main/java/io/github/problem4j/spring/web/resolver/ServerWebInputProblemResolver.java
index 54863550..756efb8f 100644
--- a/problem4j-spring-web/src/main/java/io/github/problem4j/spring/web/resolver/ServerWebInputProblemResolver.java
+++ b/problem4j-spring-web/src/main/java/io/github/problem4j/spring/web/resolver/ServerWebInputProblemResolver.java
@@ -56,7 +56,7 @@ public class ServerWebInputProblemResolver extends AbstractProblemResolver {
 
   private final TypeMismatchProblemResolver typeMismatchProblemResolver;
   private final MethodParameterSupport methodParameterSupport;
-  private final TypeNameMapper typeNameMapper;
+  private final JacksonErrorHelper jacksonErrorHelper;
 
   /** Creates a new {@link ServerWebInputProblemResolver} with default problem format. */
   public ServerWebInputProblemResolver() {
@@ -105,7 +105,7 @@ public ServerWebInputProblemResolver(
     super(ServerWebInputException.class, problemFormat);
     this.typeMismatchProblemResolver = typeMismatchProblemResolver;
     this.methodParameterSupport = methodParameterSupport;
-    this.typeNameMapper = typeNameMapper;
+    jacksonErrorHelper = new JacksonErrorHelper(problemFormat, typeNameMapper);
   }
 
   /**
@@ -161,7 +161,7 @@ private ProblemBuilder tryAppendingPropertyFromMethodParameter(
 
   private ProblemBuilder resolveDecodingException(DecodingException ex) {
     if (ex.getCause() instanceof MismatchedInputException e) {
-      return JacksonErrorHelper.resolveMismatchedInput(e, typeNameMapper);
+      return jacksonErrorHelper.resolveMismatchedInput(e);
     }
     return Problem.builder().status(HttpStatus.BAD_REQUEST.value());
   }
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/BindingPrimitiveWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/BindingPrimitiveWebFluxTest.java
index adbff332..17bb9fbf 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/BindingPrimitiveWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/BindingPrimitiveWebFluxTest.java
@@ -40,7 +40,10 @@
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
     webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
-    properties = {"spring.jackson.deserialization.fail-on-null-for-primitives=true"})
+    properties = {
+      "problem4j.detail-format=lowercase",
+      "spring.jackson.deserialization.fail-on-null-for-primitives=true"
+    })
 class BindingPrimitiveWebFluxTest {
 
   @Autowired private WebTestClient webTestClient;
@@ -136,7 +139,7 @@ void givenMalformedPrimitive_whenPost_thenReturnProblem(String path, String json
               Problem expected =
                   Problem.builder()
                       .status(HttpStatus.BAD_REQUEST.value())
-                      .detail(TYPE_MISMATCH_DETAIL)
+                      .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                       .extension(PROPERTY_EXTENSION, "value")
                       .extension(KIND_EXTENSION, expectedKind)
                       .build();
@@ -239,7 +242,7 @@ void givenMalformedNested_whenPost_thenReturnProblem(String path, String json) {
                   .isEqualTo(
                       Problem.builder()
                           .status(HttpStatus.BAD_REQUEST.value())
-                          .detail(TYPE_MISMATCH_DETAIL)
+                          .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                           .extension(PROPERTY_EXTENSION, "nested.value")
                           .extension(KIND_EXTENSION, expectedKind)
                           .build());
@@ -285,7 +288,7 @@ void givenEmptyStringPrimitive_whenPost_thenReturnProblem(String path, String js
                   .isEqualTo(
                       Problem.builder()
                           .status(HttpStatus.BAD_REQUEST.value())
-                          .detail(TYPE_MISMATCH_DETAIL)
+                          .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                           .extension(PROPERTY_EXTENSION, "value")
                           .extension(KIND_EXTENSION, expectedKind)
                           .build());
@@ -318,7 +321,7 @@ void givenOverflowPrimitive_whenPost_thenReturnProblem(String path, String json)
               Problem expected =
                   Problem.builder()
                       .status(HttpStatus.BAD_REQUEST.value())
-                      .detail(TYPE_MISMATCH_DETAIL)
+                      .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                       .extension(PROPERTY_EXTENSION, "value")
                       .extension(KIND_EXTENSION, "integer")
                       .build();
@@ -347,7 +350,7 @@ void givenNullPrimitive_whenPost_thenReturnProblem() {
               Problem expected =
                   Problem.builder()
                       .status(HttpStatus.BAD_REQUEST.value())
-                      .detail(TYPE_MISMATCH_DETAIL)
+                      .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                       .extension(PROPERTY_EXTENSION, "value")
                       .extension(KIND_EXTENSION, "integer")
                       .build();
@@ -411,7 +414,7 @@ void givenMalformedComplexObject_whenPost_thenReturnProblemWithFirstInvalidField
                     .isEqualTo(
                         Problem.builder()
                             .status(HttpStatus.BAD_REQUEST.value())
-                            .detail(TYPE_MISMATCH_DETAIL)
+                            .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                             .extension(PROPERTY_EXTENSION, expectedProperty)
                             .extension(KIND_EXTENSION, expectedKind)
                             .build()));
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ErrorResponseWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ErrorResponseWebFluxTest.java
index 11d2a85d..166d53ba 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ErrorResponseWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ErrorResponseWebFluxTest.java
@@ -34,7 +34,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class ErrorResponseWebFluxTest {
 
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ErrorWebExceptionHandlerWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ErrorWebExceptionHandlerWebFluxTest.java
index 236ad60f..4e8ccae2 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ErrorWebExceptionHandlerWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ErrorWebExceptionHandlerWebFluxTest.java
@@ -34,7 +34,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class ErrorWebExceptionHandlerWebFluxTest {
 
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MalformedMultipartWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MalformedMultipartWebFluxTest.java
index 74388c80..55043105 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MalformedMultipartWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MalformedMultipartWebFluxTest.java
@@ -35,7 +35,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class MalformedMultipartWebFluxTest {
 
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MaxUploadSizeExceededWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MaxUploadSizeExceededWebFluxTest.java
index d018e795..6a375536 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MaxUploadSizeExceededWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MaxUploadSizeExceededWebFluxTest.java
@@ -36,7 +36,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class MaxUploadSizeExceededWebFluxTest {
 
@@ -57,7 +58,7 @@ void givenMaxUploadSizeExceeded_shouldReturnProblem() {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.PAYLOAD_TOO_LARGE.value())
-                .detail(MAX_UPLOAD_SIZE_EXCEEDED_DETAIL)
+                .detail(MAX_UPLOAD_SIZE_EXCEEDED_DETAIL.toLowerCase())
                 .extension(MAX_EXTENSION, 1)
                 .build());
   }
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MethodNotAllowedWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MethodNotAllowedWebFluxTest.java
index cf5b1381..59d09170 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MethodNotAllowedWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MethodNotAllowedWebFluxTest.java
@@ -34,7 +34,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class MethodNotAllowedWebFluxTest {
 
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MissingParameterWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MissingParameterWebFluxTest.java
index aa57beca..deb70de0 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MissingParameterWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/MissingParameterWebFluxTest.java
@@ -52,7 +52,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class MissingParameterWebFluxTest {
 
@@ -76,7 +77,7 @@ void givenRequestWithoutPathVariable_shouldReturnProblem() {
                   .isEqualTo(
                       Problem.builder()
                           .status(HttpStatus.BAD_REQUEST.value())
-                          .detail(MISSING_PATH_VARIABLE_DETAIL)
+                          .detail(MISSING_PATH_VARIABLE_DETAIL.toLowerCase())
                           .extension(NAME_EXTENSION, "var")
                           .build());
             });
@@ -112,7 +113,7 @@ void givenRequestWithoutRequestParam_shouldReturnProblem() {
                   .isEqualTo(
                       Problem.builder()
                           .status(HttpStatus.BAD_REQUEST.value())
-                          .detail(MISSING_REQUEST_PARAM_DETAIL)
+                          .detail(MISSING_REQUEST_PARAM_DETAIL.toLowerCase())
                           .extension(PARAM_EXTENSION, "param")
                           .extension(KIND_EXTENSION, "string")
                           .build());
@@ -154,7 +155,7 @@ void givenRequestWithoutRequestPart_shouldReturnProblem() {
                   .isEqualTo(
                       Problem.builder()
                           .status(HttpStatus.BAD_REQUEST.value())
-                          .detail(MISSING_REQUEST_PART_DETAIL)
+                          .detail(MISSING_REQUEST_PART_DETAIL.toLowerCase())
                           .extension(PARAM_EXTENSION, "file")
                           .build());
             });
@@ -202,7 +203,7 @@ void givenRequestWithoutRequestHeader_shouldReturnProblem() {
                   .isEqualTo(
                       Problem.builder()
                           .status(HttpStatus.BAD_REQUEST.value())
-                          .detail(MISSING_HEADER_DETAIL)
+                          .detail(MISSING_HEADER_DETAIL.toLowerCase())
                           .extension(HEADER_EXTENSION, "X-Custom-Header")
                           .build());
             });
@@ -239,7 +240,7 @@ void givenRequestWithoutCookieValue_shouldReturnProblem() {
                   .isEqualTo(
                       Problem.builder()
                           .status(HttpStatus.BAD_REQUEST.value())
-                          .detail(MISSING_COOKIE_DETAIL)
+                          .detail(MISSING_COOKIE_DETAIL.toLowerCase())
                           .extension(COOKIE_EXTENSION, "x_session")
                           .build());
             });
@@ -276,7 +277,7 @@ void givenRequestWithoutRequestAttribute_shouldReturnProblem() {
                   .isEqualTo(
                       Problem.builder()
                           .status(HttpStatus.BAD_REQUEST.value())
-                          .detail(MISSING_REQUEST_ATTRIBUTE_DETAIL)
+                          .detail(MISSING_REQUEST_ATTRIBUTE_DETAIL.toLowerCase())
                           .extension(ATTRIBUTE_EXTENSION, "attr")
                           .build());
             });
@@ -297,7 +298,7 @@ void givenRequestWithoutSessionAttribute_shouldReturnProblem() {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(MISSING_SESSION_ATTRIBUTE_DETAIL)
+                .detail(MISSING_SESSION_ATTRIBUTE_DETAIL.toLowerCase())
                 .extension(ATTRIBUTE_EXTENSION, "attr")
                 .build());
   }
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/NotAcceptableWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/NotAcceptableWebFluxTest.java
index 8f240b40..1e9c426b 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/NotAcceptableWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/NotAcceptableWebFluxTest.java
@@ -35,7 +35,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class NotAcceptableWebFluxTest {
 
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/NotFoundNoHandlerFoundWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/NotFoundNoHandlerFoundWebFluxTest.java
index d0d0e911..a8468bfd 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/NotFoundNoHandlerFoundWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/NotFoundNoHandlerFoundWebFluxTest.java
@@ -34,7 +34,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class NotFoundNoHandlerFoundWebFluxTest {
 
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/NotFoundNoResourceFoundWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/NotFoundNoResourceFoundWebFluxTest.java
index 6d02d174..560e2da5 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/NotFoundNoResourceFoundWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/NotFoundNoResourceFoundWebFluxTest.java
@@ -36,7 +36,8 @@
     classes = {WebFluxTestApp.class},
     properties = {
       "spring.webflux.static-path-pattern=/**",
-      "spring.web.resources.static-locations=classpath:/static/"
+      "spring.web.resources.static-locations=classpath:/static/",
+      "problem4j.detail-format=lowercase"
     },
     webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
 @AutoConfigureWebTestClient
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ProblemAdviceWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ProblemAdviceWebFluxTest.java
index 2e1f3eea..1bf10cd1 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ProblemAdviceWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ProblemAdviceWebFluxTest.java
@@ -37,7 +37,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class ProblemAdviceWebFluxTest {
 
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ProblemOverrideWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ProblemOverrideWebFluxTest.java
index 4e35feee..280ada18 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ProblemOverrideWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ProblemOverrideWebFluxTest.java
@@ -40,7 +40,8 @@
     properties = {
       "problem4j.type-override=https://example.org/type/{problem.type}",
       "problem4j.instance-override=https://example.org/trace/{context.traceId}",
-      "problem4j.tracing-header-name=X-Trace-Id"
+      "problem4j.tracing-header-name=X-Trace-Id",
+      "problem4j.detail-format=lowercase"
     },
     webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
 @AutoConfigureWebTestClient
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ResponseStatusAnnotatedExceptionWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ResponseStatusAnnotatedExceptionWebFluxTest.java
index c4e516be..70c5a499 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ResponseStatusAnnotatedExceptionWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ResponseStatusAnnotatedExceptionWebFluxTest.java
@@ -34,7 +34,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class ResponseStatusAnnotatedExceptionWebFluxTest {
 
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ResponseStatusExceptionWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ResponseStatusExceptionWebFluxTest.java
index 9c07a179..51c11340 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ResponseStatusExceptionWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ResponseStatusExceptionWebFluxTest.java
@@ -34,7 +34,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class ResponseStatusExceptionWebFluxTest {
 
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/TypeMismatchWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/TypeMismatchWebFluxTest.java
index 35727dde..b7e193e7 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/TypeMismatchWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/TypeMismatchWebFluxTest.java
@@ -37,7 +37,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class TypeMismatchWebFluxTest {
 
@@ -58,7 +59,7 @@ void givenRequestWithInvalidPathVariable_shouldReturnProblem() {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(TYPE_MISMATCH_DETAIL)
+                .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                 .extension(PROPERTY_EXTENSION, "id")
                 .extension(KIND_EXTENSION, "integer")
                 .build());
@@ -94,7 +95,7 @@ void givenRequestWithInvalidParameterType_shouldReturnProblem() {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(TYPE_MISMATCH_DETAIL)
+                .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                 .extension(PROPERTY_EXTENSION, "id")
                 .extension(KIND_EXTENSION, "integer")
                 .build());
@@ -131,7 +132,7 @@ void givenRequestWithInvalidRequestHeader_shouldReturnProblem() {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(TYPE_MISMATCH_DETAIL)
+                .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                 .extension(PROPERTY_EXTENSION, "X-Id")
                 .extension(KIND_EXTENSION, "integer")
                 .build());
@@ -167,7 +168,7 @@ void givenRequestWithInvalidCookieValue_shouldReturnProblem() {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(TYPE_MISMATCH_DETAIL)
+                .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                 .extension(PROPERTY_EXTENSION, "id")
                 .extension(KIND_EXTENSION, "integer")
                 .build());
@@ -206,7 +207,7 @@ void givenRequestWithInvalidEnumInRequestBody_shouldReturnProblem() {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(TYPE_MISMATCH_DETAIL)
+                .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                 .extension(PROPERTY_EXTENSION, "status")
                 .extension(KIND_EXTENSION, "enum")
                 .build());
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/UnsupportedMediaTypeWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/UnsupportedMediaTypeWebFluxTest.java
index cf37f19c..bf81007f 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/UnsupportedMediaTypeWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/UnsupportedMediaTypeWebFluxTest.java
@@ -35,7 +35,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class UnsupportedMediaTypeWebFluxTest {
 
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateMethodArgumentFailingWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateMethodArgumentFailingWebFluxTest.java
index 9cf2f606..44c439a7 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateMethodArgumentFailingWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateMethodArgumentFailingWebFluxTest.java
@@ -44,7 +44,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class ValidateMethodArgumentFailingWebFluxTest {
 
@@ -70,7 +71,7 @@ void givenTooShortPathVariable_shouldReturnValidationProblem() {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION, List.of(Map.of("field", "idVar", "error", VIOLATION_ERROR)))
                 .build());
@@ -99,7 +100,7 @@ void givenTooShortRequestParam_shouldReturnValidationProblem() {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION,
                     List.of(Map.of("field", "queryParam", "error", VIOLATION_ERROR)))
@@ -125,7 +126,7 @@ void givenTooShortRequestHeader_shouldReturnValidationProblem() {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION,
                     List.of(Map.of("field", "xCustomHeader", "error", VIOLATION_ERROR)))
@@ -152,7 +153,7 @@ void givenTooShortCookieValue_shouldReturnValidationProblem() {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION,
                     List.of(Map.of("field", "xSession", "error", VIOLATION_ERROR)))
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateMethodArgumentFailingWithAdaptingWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateMethodArgumentFailingWithAdaptingWebFluxTest.java
index 7c97ea94..935c977a 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateMethodArgumentFailingWithAdaptingWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateMethodArgumentFailingWithAdaptingWebFluxTest.java
@@ -42,7 +42,10 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    properties = {"spring.validation.method.adapt-constraint-violations=true"},
+    properties = {
+      "spring.validation.method.adapt-constraint-violations=true",
+      "problem4j.detail-format=lowercase"
+    },
     webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
 @AutoConfigureWebTestClient
 class ValidateMethodArgumentFailingWithAdaptingWebFluxTest {
@@ -71,7 +74,7 @@ void givenTooShortPathVariable_shouldReturnValidationProblem() {
                     .isEqualTo(
                         Problem.builder()
                             .status(HttpStatus.BAD_REQUEST.value())
-                            .detail(VALIDATION_FAILED_DETAIL)
+                            .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                             .extension(
                                 ERRORS_EXTENSION,
                                 List.of(Map.of("field", "id", "error", VIOLATION_ERROR)))
@@ -103,7 +106,7 @@ void givenTooShortRequestParam_shouldReturnValidationProblem() {
                     .isEqualTo(
                         Problem.builder()
                             .status(HttpStatus.BAD_REQUEST.value())
-                            .detail(VALIDATION_FAILED_DETAIL)
+                            .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                             .extension(
                                 ERRORS_EXTENSION,
                                 List.of(Map.of("field", "query", "error", VIOLATION_ERROR)))
@@ -131,7 +134,7 @@ void givenTooShortRequestHeader_shouldReturnValidationProblem() {
                     .isEqualTo(
                         Problem.builder()
                             .status(HttpStatus.BAD_REQUEST.value())
-                            .detail(VALIDATION_FAILED_DETAIL)
+                            .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                             .extension(
                                 ERRORS_EXTENSION,
                                 List.of(
@@ -160,7 +163,7 @@ void givenTooShortCookieValue_shouldReturnValidationProblem() {
                     .isEqualTo(
                         Problem.builder()
                             .status(HttpStatus.BAD_REQUEST.value())
-                            .detail(VALIDATION_FAILED_DETAIL)
+                            .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                             .extension(
                                 ERRORS_EXTENSION,
                                 List.of(Map.of("field", "x_session", "error", VIOLATION_ERROR)))
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateMethodArgumentPassingWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateMethodArgumentPassingWebFluxTest.java
index f7a20ba6..d7963a44 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateMethodArgumentPassingWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateMethodArgumentPassingWebFluxTest.java
@@ -35,7 +35,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class ValidateMethodArgumentPassingWebFluxTest {
 
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateRequestBodyWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateRequestBodyWebFluxTest.java
index bd769468..dbd3f7dc 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateRequestBodyWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/ValidateRequestBodyWebFluxTest.java
@@ -45,7 +45,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class ValidateRequestBodyWebFluxTest {
 
@@ -70,7 +71,7 @@ void givenInvalidRequestBody_shouldReturnProblem() {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION,
                     List.of(Map.of("field", "name", "error", "must not be blank")))
@@ -99,7 +100,7 @@ void givenGlobalValidationViolation_shouldReturnProblemWithoutFieldName() {
                   .isEqualTo(
                       Problem.builder()
                           .status(HttpStatus.BAD_REQUEST.value())
-                          .detail(VALIDATION_FAILED_DETAIL)
+                          .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                           .extension(ERRORS_EXTENSION, List.of(error))
                           .build());
             });
diff --git a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/WebExchangeBindExceptionWebFluxTest.java b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/WebExchangeBindExceptionWebFluxTest.java
index bd11a590..c420e37b 100644
--- a/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/WebExchangeBindExceptionWebFluxTest.java
+++ b/problem4j-spring-webflux/src/test/java/io/github/problem4j/spring/webflux/integration/WebExchangeBindExceptionWebFluxTest.java
@@ -38,7 +38,8 @@
 
 @SpringBootTest(
     classes = {WebFluxTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 @AutoConfigureWebTestClient
 class WebExchangeBindExceptionWebFluxTest {
 
@@ -60,7 +61,7 @@ void givenModelAttributeTypeMismatch_shouldReturnBadRequestProblem() {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION, List.of(Map.of("field", "number", "error", "is not valid")))
                 .build());
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/BindingPrimitiveWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/BindingPrimitiveWebMvcTest.java
index 3af2d8e5..2358baea 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/BindingPrimitiveWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/BindingPrimitiveWebMvcTest.java
@@ -45,7 +45,10 @@
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
     webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
-    properties = {"spring.jackson.deserialization.fail-on-null-for-primitives=true"})
+    properties = {
+      "spring.jackson.deserialization.fail-on-null-for-primitives=true",
+      "problem4j.detail-format=lowercase"
+    })
 class BindingPrimitiveWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
@@ -139,7 +142,7 @@ void givenMalformedPrimitive_whenPost_thenReturnProblem(String path, String json
     Problem expected =
         Problem.builder()
             .status(HttpStatus.BAD_REQUEST.value())
-            .detail(TYPE_MISMATCH_DETAIL)
+            .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
             .extension(PROPERTY_EXTENSION, "value")
             .extension(KIND_EXTENSION, expectedKind)
             .build();
@@ -238,7 +241,7 @@ void givenMalformedNested_whenPost_thenReturnProblem(String path, String json)
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(TYPE_MISMATCH_DETAIL)
+                .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                 .extension(PROPERTY_EXTENSION, "nested.value")
                 .extension(KIND_EXTENSION, expectedKind)
                 .build());
@@ -282,7 +285,7 @@ void givenEmptyStringPrimitive_whenPost_thenReturnProblem(String path, String js
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(TYPE_MISMATCH_DETAIL)
+                .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                 .extension(PROPERTY_EXTENSION, "value")
                 .extension(KIND_EXTENSION, expectedKind)
                 .build());
@@ -313,7 +316,7 @@ void givenOverflowPrimitive_whenPost_thenReturnProblem(String path, String json)
     Problem expected =
         Problem.builder()
             .status(HttpStatus.BAD_REQUEST.value())
-            .detail(TYPE_MISMATCH_DETAIL)
+            .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
             .extension(PROPERTY_EXTENSION, "value")
             .extension(KIND_EXTENSION, "integer")
             .build();
@@ -342,7 +345,7 @@ void givenNullPrimitive_whenPost_thenReturnProblem() throws JsonProcessingExcept
     Problem expected =
         Problem.builder()
             .status(HttpStatus.BAD_REQUEST.value())
-            .detail(TYPE_MISMATCH_DETAIL)
+            .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
             .extension(PROPERTY_EXTENSION, "value")
             .extension(KIND_EXTENSION, "integer")
             .build();
@@ -402,7 +405,7 @@ void givenMalformedComplexObject_whenPost_thenReturnProblemWithFirstInvalidField
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(TYPE_MISMATCH_DETAIL)
+                .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                 .extension(PROPERTY_EXTENSION, expectedProperty)
                 .extension(KIND_EXTENSION, expectedKind)
                 .build());
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ErrorControllerWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ErrorControllerWebMvcTest.java
index ee0865a3..b5f10bc1 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ErrorControllerWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ErrorControllerWebMvcTest.java
@@ -36,7 +36,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class ErrorControllerWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ErrorResponseWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ErrorResponseWebMvcTest.java
index 7998c6ee..a8f9f587 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ErrorResponseWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ErrorResponseWebMvcTest.java
@@ -35,7 +35,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class ErrorResponseWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MalformedMultipartWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MalformedMultipartWebMvcTest.java
index 5b958829..5b880ab9 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MalformedMultipartWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MalformedMultipartWebMvcTest.java
@@ -42,7 +42,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class MalformedMultipartWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
@@ -68,7 +69,7 @@ void givenRequestWithMalformedRequestPart_shouldReturnProblem() throws Exception
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(MISSING_REQUEST_PART_DETAIL)
+                .detail(MISSING_REQUEST_PART_DETAIL.toLowerCase())
                 .extension(PARAM_EXTENSION, "file")
                 .build());
   }
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MaxUploadSizeExceededWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MaxUploadSizeExceededWebMvcTest.java
index 33352884..8597a0aa 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MaxUploadSizeExceededWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MaxUploadSizeExceededWebMvcTest.java
@@ -45,7 +45,8 @@
     webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
     properties = {
       "spring.servlet.multipart.max-file-size=1KB",
-      "spring.servlet.multipart.max-request-size=1KB"
+      "spring.servlet.multipart.max-request-size=1KB",
+      "problem4j.detail-format=lowercase"
     })
 class MaxUploadSizeExceededWebMvcTest {
 
@@ -72,7 +73,7 @@ void givenMaxUploadSizeExceeded_shouldReturnProblem() throws Exception {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.PAYLOAD_TOO_LARGE.value())
-                .detail(MAX_UPLOAD_SIZE_EXCEEDED_DETAIL)
+                .detail(MAX_UPLOAD_SIZE_EXCEEDED_DETAIL.toLowerCase())
                 .build());
   }
 
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MethodArgumentNotValidWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MethodArgumentNotValidWebMvcTest.java
index 8757cd6b..ded5623a 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MethodArgumentNotValidWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MethodArgumentNotValidWebMvcTest.java
@@ -40,7 +40,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class MethodArgumentNotValidWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
@@ -60,7 +61,7 @@ void givenModelAttributeTypeMismatch_shouldReturnBadRequestProblem() throws Exce
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION,
                     List.of(Map.of("field", "number", "error", IS_NOT_VALID_ERROR)))
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MethodNotAllowedWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MethodNotAllowedWebMvcTest.java
index ece06d71..aace82be 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MethodNotAllowedWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MethodNotAllowedWebMvcTest.java
@@ -35,7 +35,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class MethodNotAllowedWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MissingParameterWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MissingParameterWebMvcTest.java
index 61c427c6..20bbf29a 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MissingParameterWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/MissingParameterWebMvcTest.java
@@ -55,7 +55,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class MissingParameterWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
@@ -75,7 +76,7 @@ void givenRequestWithoutPathVariable_shouldReturnProblem() throws Exception {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(MISSING_PATH_VARIABLE_DETAIL)
+                .detail(MISSING_PATH_VARIABLE_DETAIL.toLowerCase())
                 .extension(NAME_EXTENSION, "var")
                 .build());
   }
@@ -103,7 +104,7 @@ void givenRequestWithoutRequestParam_shouldReturnProblem() throws Exception {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(MISSING_REQUEST_PARAM_DETAIL)
+                .detail(MISSING_REQUEST_PARAM_DETAIL.toLowerCase())
                 .extension(PARAM_EXTENSION, "param")
                 .extension(KIND_EXTENSION, "string")
                 .build());
@@ -138,7 +139,7 @@ void givenRequestWithoutRequestPartParam_shouldReturnProblem() throws Exception
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(MISSING_REQUEST_PART_DETAIL)
+                .detail(MISSING_REQUEST_PART_DETAIL.toLowerCase())
                 .extension(PARAM_EXTENSION, "file")
                 .build());
   }
@@ -193,7 +194,7 @@ void givenRequestWithoutRequestHeader_shouldReturnProblem() throws Exception {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(MISSING_HEADER_DETAIL)
+                .detail(MISSING_HEADER_DETAIL.toLowerCase())
                 .extension(HEADER_EXTENSION, "X-Custom-Header")
                 .build());
   }
@@ -221,7 +222,7 @@ void givenRequestWithoutCookieValue_shouldReturnProblem() throws Exception {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(MISSING_COOKIE_DETAIL)
+                .detail(MISSING_COOKIE_DETAIL.toLowerCase())
                 .extension(COOKIE_EXTENSION, "x_session")
                 .build());
   }
@@ -249,7 +250,7 @@ void givenRequestWithoutRequestAttribute_shouldReturnProblem() throws Exception
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(MISSING_REQUEST_ATTRIBUTE_DETAIL)
+                .detail(MISSING_REQUEST_ATTRIBUTE_DETAIL.toLowerCase())
                 .extension(ATTRIBUTE_EXTENSION, "attr")
                 .build());
   }
@@ -265,7 +266,7 @@ void givenRequestWithoutSessionAttribute_shouldReturnProblem() throws Exception
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(MISSING_SESSION_ATTRIBUTE_DETAIL)
+                .detail(MISSING_SESSION_ATTRIBUTE_DETAIL.toLowerCase())
                 .extension(ATTRIBUTE_EXTENSION, "attr")
                 .build());
   }
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/NotAcceptableWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/NotAcceptableWebMvcTest.java
index 4f20df5b..758ef8cf 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/NotAcceptableWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/NotAcceptableWebMvcTest.java
@@ -40,7 +40,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class NotAcceptableWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/NotFoundNoHandlerFoundWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/NotFoundNoHandlerFoundWebMvcTest.java
index e6174911..66e921b4 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/NotFoundNoHandlerFoundWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/NotFoundNoHandlerFoundWebMvcTest.java
@@ -38,7 +38,8 @@
     webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
     properties = {
       "spring.mvc.throw-exception-if-no-handler-found=true",
-      "spring.web.resources.add-mappings=false"
+      "spring.web.resources.add-mappings=false",
+      "problem4j.detail-format=lowercase"
     })
 class NotFoundNoHandlerFoundWebMvcTest {
 
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/NotFoundNoResourceFoundWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/NotFoundNoResourceFoundWebMvcTest.java
index 76fc67da..15aa5e45 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/NotFoundNoResourceFoundWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/NotFoundNoResourceFoundWebMvcTest.java
@@ -36,7 +36,7 @@
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
     webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
-    properties = {"spring.web.resources.add-mappings=true"})
+    properties = {"spring.web.resources.add-mappings=true", "problem4j.detail-format=lowercase"})
 class NotFoundNoResourceFoundWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ProblemAdviceWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ProblemAdviceWebMvcTest.java
index 06e1046e..29375fd6 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ProblemAdviceWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ProblemAdviceWebMvcTest.java
@@ -38,7 +38,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class ProblemAdviceWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ProblemOverrideWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ProblemOverrideWebMvcTest.java
index e6888b8c..1506c2ca 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ProblemOverrideWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ProblemOverrideWebMvcTest.java
@@ -43,7 +43,8 @@
     properties = {
       "problem4j.type-override=https://example.org/type/{problem.type}",
       "problem4j.instance-override=https://example.org/trace/{context.traceId}",
-      "problem4j.tracing-header-name=X-Trace-Id"
+      "problem4j.tracing-header-name=X-Trace-Id",
+      "problem4j.detail-format=lowercase"
     })
 class ProblemOverrideWebMvcTest {
 
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ResponseStatusAnnotatedExceptionWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ResponseStatusAnnotatedExceptionWebMvcTest.java
index 75c38483..bc46e2fd 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ResponseStatusAnnotatedExceptionWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ResponseStatusAnnotatedExceptionWebMvcTest.java
@@ -35,7 +35,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class ResponseStatusAnnotatedExceptionWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ResponseStatusExceptionWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ResponseStatusExceptionWebMvcTest.java
index 6959d4d5..b11c4d82 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ResponseStatusExceptionWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ResponseStatusExceptionWebMvcTest.java
@@ -35,7 +35,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class ResponseStatusExceptionWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/TypeMismatchWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/TypeMismatchWebMvcTest.java
index d0033cd0..c512eea8 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/TypeMismatchWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/TypeMismatchWebMvcTest.java
@@ -43,7 +43,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class TypeMismatchWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
@@ -63,7 +64,7 @@ void givenRequestWithInvalidPathVariable_shouldReturnProblem() throws Exception
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(TYPE_MISMATCH_DETAIL)
+                .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                 .extension(PROPERTY_EXTENSION, "id")
                 .extension(KIND_EXTENSION, "integer")
                 .build());
@@ -92,7 +93,7 @@ void givenRequestWithInvalidParameterType_shouldReturnProblem() throws Exception
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(TYPE_MISMATCH_DETAIL)
+                .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                 .extension(PROPERTY_EXTENSION, "id")
                 .extension(KIND_EXTENSION, "integer")
                 .build());
@@ -127,7 +128,7 @@ void givenRequestWithInvalidRequestHeader_shouldReturnProblem() throws Exception
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(TYPE_MISMATCH_DETAIL)
+                .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                 .extension(PROPERTY_EXTENSION, "X-Id")
                 .extension(KIND_EXTENSION, "integer")
                 .build());
@@ -167,7 +168,7 @@ void givenRequestWithInvalidCookieValue_shouldReturnProblem() throws Exception {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(TYPE_MISMATCH_DETAIL)
+                .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                 .extension(PROPERTY_EXTENSION, "id")
                 .extension(KIND_EXTENSION, "integer")
                 .build());
@@ -208,7 +209,7 @@ void givenRequestWithInvalidEnumInRequestBody_shouldReturnProblem()
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(TYPE_MISMATCH_DETAIL)
+                .detail(TYPE_MISMATCH_DETAIL.toLowerCase())
                 .extension(PROPERTY_EXTENSION, "status")
                 .extension(KIND_EXTENSION, "enum")
                 .build());
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/UnsupportedMediaTypeWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/UnsupportedMediaTypeWebMvcTest.java
index a9244d58..68a1472a 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/UnsupportedMediaTypeWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/UnsupportedMediaTypeWebMvcTest.java
@@ -38,7 +38,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class UnsupportedMediaTypeWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateMethodArgumentFailingWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateMethodArgumentFailingWebMvcTest.java
index 9174091f..4be3128a 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateMethodArgumentFailingWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateMethodArgumentFailingWebMvcTest.java
@@ -46,7 +46,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class ValidateMethodArgumentFailingWebMvcTest {
 
   private static final String VIOLATION_ERROR = "size must be between 5 and " + Integer.MAX_VALUE;
@@ -68,7 +69,7 @@ void givenTooShortPathVariable_shouldReturnValidationProblem() throws Exception
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION, List.of(Map.of("field", "idVar", "error", VIOLATION_ERROR)))
                 .build());
@@ -88,7 +89,7 @@ void givenTooShortRequestParam_shouldReturnValidationProblem() throws Exception
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION,
                     List.of(Map.of("field", "queryParam", "error", VIOLATION_ERROR)))
@@ -116,7 +117,7 @@ void givenTooShortRequestHeader_shouldReturnValidationProblem() throws Exception
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION,
                     List.of(Map.of("field", "xCustomHeader", "error", VIOLATION_ERROR)))
@@ -144,7 +145,7 @@ void givenTooShortCookieValue_shouldReturnValidationProblem() throws Exception {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION,
                     List.of(Map.of("field", "xSession", "error", VIOLATION_ERROR)))
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateMethodArgumentFailingWithAdaptionWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateMethodArgumentFailingWithAdaptionWebMvcTest.java
index 493bd863..db92b055 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateMethodArgumentFailingWithAdaptionWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateMethodArgumentFailingWithAdaptionWebMvcTest.java
@@ -46,7 +46,10 @@
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
     webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
-    properties = {"spring.validation.method.adapt-constraint-violations=true"})
+    properties = {
+      "spring.validation.method.adapt-constraint-violations=true",
+      "problem4j.detail-format=lowercase"
+    })
 class ValidateMethodArgumentFailingWithAdaptionWebMvcTest {
 
   private static final String VIOLATION_ERROR = "size must be between 5 and " + Integer.MAX_VALUE;
@@ -67,7 +70,7 @@ void givenTooShortPathVariable_shouldReturnValidationProblem() throws Exception
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION, List.of(Map.of("field", "id", "error", VIOLATION_ERROR)))
                 .build());
@@ -87,7 +90,7 @@ void givenTooShortRequestParam_shouldReturnValidationProblem() throws Exception
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION, List.of(Map.of("field", "query", "error", VIOLATION_ERROR)))
                 .build());
@@ -114,7 +117,7 @@ void givenTooShortRequestHeader_shouldReturnValidationProblem() throws Exception
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION,
                     List.of(Map.of("field", "X-Custom-Header", "error", VIOLATION_ERROR)))
@@ -142,7 +145,7 @@ void givenTooShortCookieValue_shouldReturnValidationProblem() throws Exception {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION,
                     List.of(Map.of("field", "x_session", "error", VIOLATION_ERROR)))
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateMethodArgumentPassingWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateMethodArgumentPassingWebMvcTest.java
index 0b5ab11d..e8fd33f2 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateMethodArgumentPassingWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateMethodArgumentPassingWebMvcTest.java
@@ -38,7 +38,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class ValidateMethodArgumentPassingWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
diff --git a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateRequestBodyWebMvcTest.java b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateRequestBodyWebMvcTest.java
index cb7fa013..0b49f82f 100644
--- a/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateRequestBodyWebMvcTest.java
+++ b/problem4j-spring-webmvc/src/test/java/io/github/problem4j/spring/webmvc/integration/ValidateRequestBodyWebMvcTest.java
@@ -49,7 +49,8 @@
 
 @SpringBootTest(
     classes = {WebMvcTestApp.class},
-    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+    webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+    properties = {"problem4j.detail-format=lowercase"})
 class ValidateRequestBodyWebMvcTest {
 
   @Autowired private TestRestTemplate restTemplate;
@@ -71,7 +72,7 @@ void givenInvalidRequestBody_shouldReturnProblem() throws Exception {
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(
                     ERRORS_EXTENSION,
                     List.of(Map.of("field", "name", "error", "must not be blank")))
@@ -96,7 +97,7 @@ void givenGlobalValidationViolation_shouldReturnProblemWithoutFieldName() throws
         .isEqualTo(
             Problem.builder()
                 .status(HttpStatus.BAD_REQUEST.value())
-                .detail(VALIDATION_FAILED_DETAIL)
+                .detail(VALIDATION_FAILED_DETAIL.toLowerCase())
                 .extension(ERRORS_EXTENSION, List.of(error))
                 .build());
   }