diff --git a/libcxx/include/__config b/libcxx/include/__config
index 7cc07fac3a07..d8b0a99a1f54 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -249,7 +249,7 @@ template <unsigned> struct __static_assert_check {};
 #define constexpr const
 #endif
 
-#ifndef __has_feature(__x)
+#ifndef __has_feature
 #define __has_feature(__x) 0
 #endif