diff --git a/unittests/Support/raw_pwrite_stream_test.cpp b/unittests/Support/raw_pwrite_stream_test.cpp
index 65625fcddd4..08b2f90d605 100644
--- a/unittests/Support/raw_pwrite_stream_test.cpp
+++ b/unittests/Support/raw_pwrite_stream_test.cpp
@@ -44,7 +44,7 @@ TEST(raw_pwrite_ostreamTest, TestSVector) {
 #endif
 }
 
-#ifdef _MSC_VER
+#ifdef _WIN32
 #define setenv(name, var, ignore) _putenv_s(name, var)
 #endif