diff --git a/openmp/runtime/src/kmp_global.cpp b/openmp/runtime/src/kmp_global.cpp
--- a/openmp/runtime/src/kmp_global.cpp
+++ b/openmp/runtime/src/kmp_global.cpp
@@ -175,7 +175,7 @@
 #if KMP_OS_LINUX && defined(KMP_TDATA_GTID)
 int __kmp_gtid_mode = 3; /* use __declspec(thread) TLS to store gtid */
 int __kmp_adjust_gtid_mode = FALSE;
-#elif KMP_OS_WINDOWS
+#elif KMP_OS_WINDOWS || KMP_OS_DARWIN
 int __kmp_gtid_mode = 2; /* use TLS functions to store gtid */
 int __kmp_adjust_gtid_mode = FALSE;
 #else