diff --git a/src/google/protobuf/stubs/strutil.cc b/src/google/protobuf/stubs/strutil.cc
index 4fa8e99f4f..15b6e53f1a 100644
--- a/src/google/protobuf/stubs/strutil.cc
+++ b/src/google/protobuf/stubs/strutil.cc
@@ -981,7 +981,7 @@ static const char two_ASCII_digits[100][2] = {
 };
 
 char* FastUInt32ToBufferLeft(uint32 u, char* buffer) {
-  int digits;
+  uint32 digits;
   const char *ASCII_digits = NULL;
   // The idea of this implementation is to trim the number of divides to as few
   // as possible by using multiplication and subtraction rather than mod (%),