diff --git a/googletest/test/gtest_unittest.cc b/googletest/test/gtest_unittest.cc
index 2199073d..ecffa376 100644
--- a/googletest/test/gtest_unittest.cc
+++ b/googletest/test/gtest_unittest.cc
@@ -446,7 +446,7 @@ class FormatEpochTimeInMillisAsIso8601Test : public Test {
     // tzset() distinguishes between the TZ variable being present and empty
     // and not being present, so we have to consider the case of time_zone
     // being NULL.
-#if _MSC_VER || GTEST_OS_WINDOWS_MINGW
+#if defined(_MSC_VER) || GTEST_OS_WINDOWS_MINGW
     // ...Unless it's MSVC, whose standard library's _putenv doesn't
     // distinguish between an empty and a missing variable.
     const std::string env_var =