diff --git a/libcxx/test/support/test_macros.h b/libcxx/test/support/test_macros.h
index 5ef14e54dae23..1b6473b623c53 100644
--- a/libcxx/test/support/test_macros.h
+++ b/libcxx/test/support/test_macros.h
@@ -511,7 +511,7 @@ inline Tp const& DoNotOptimize(Tp const& value) {
 #  define TEST_CONSTEXPR_OPERATOR_NEW
 #endif
 
-#if __SIZEOF_LONG_DOUBLE__ == __SIZEOF_DOUBLE__
+#if defined(_MSC_VER) || __SIZEOF_LONG_DOUBLE__ == __SIZEOF_DOUBLE__
 #  define TEST_LONG_DOUBLE_IS_DOUBLE
 #endif