diff --git a/requirements.txt b/requirements.txt
index 40dfa4c..c19a093 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1 @@
-mock==3.0.5
\ No newline at end of file
+mock==4.0.3
\ No newline at end of file
diff --git a/setup.py b/setup.py
index 1ba0067..d99a6d8 100644
--- a/setup.py
+++ b/setup.py
@@ -11,6 +11,6 @@
       keywords="music generator theory probability random song melody tune",
       include_package_data=True,
       install_requires=[
-            "mock==3.0.5",
+            "mock==4.0.3",
       ]
       )