diff --git a/bolt/exec/SortBuffer.cpp b/bolt/exec/SortBuffer.cpp
index 608933852..1aaff08c9 100644
--- a/bolt/exec/SortBuffer.cpp
+++ b/bolt/exec/SortBuffer.cpp
@@ -396,7 +396,7 @@ void SortBuffer::prepareOutput(uint32_t maxOutputRows) {
   BOLT_CHECK_GT(numInputRows_, numOutputRows_);
 
   const size_t batchSize =
-      std::min<size_t>(numInputRows_ - numOutputRows_, maxOutputRows);
+      std::min<uint64_t>(numInputRows_ - numOutputRows_, maxOutputRows);
 
   if (output_ != nullptr) {
     VectorPtr output = std::move(output_);
diff --git a/bolt/exec/SortBuffer.h b/bolt/exec/SortBuffer.h
index 8a05e9aa2..adbd76fa5 100644
--- a/bolt/exec/SortBuffer.h
+++ b/bolt/exec/SortBuffer.h
@@ -185,7 +185,7 @@ class SortBuffer {
   // sort buffer object.
   bool noMoreInput_ = false;
   // The number of received input rows.
-  size_t numInputRows_ = 0;
+  uint64_t numInputRows_ = 0;
   // Used to store the input data in row format.
   std::unique_ptr<RowContainer> data_;
   std::vector<char*> sortedRows_;
@@ -207,7 +207,7 @@ class SortBuffer {
   // 'data_->estimateRowSize()' across all accumulated data set.
   std::optional<uint64_t> estimatedOutputRowSize_{};
   // The number of rows that has been returned.
-  size_t numOutputRows_{0};
+  uint64_t numOutputRows_{0};
 
   HybridSorter sorter_;