diff --git a/googlemock/src/gmock-internal-utils.cc b/googlemock/src/gmock-internal-utils.cc
index 0a74841f..2d7c5c4e 100644
--- a/googlemock/src/gmock-internal-utils.cc
+++ b/googlemock/src/gmock-internal-utils.cc
@@ -201,7 +201,7 @@ GTEST_API_ void IllegalDoDefault(const char* file, int line) {
 constexpr char UnBase64Impl(char c, const char* const base64, char carry) {
   return *base64 == 0   ? static_cast<char>(65)
          : *base64 == c ? carry
-                        : UnBase64Impl(c, base64 + 1, carry + 1);
+                        : UnBase64Impl(c, base64 + 1, static_cast<char>(carry + 1));
 }
 
 template <size_t... I>