diff --git a/include/experimental/ratio b/include/experimental/ratio
index a00a2530e..757f24e08 100644
--- a/include/experimental/ratio
+++ b/include/experimental/ratio
@@ -74,4 +74,4 @@ _LIBCPP_END_NAMESPACE_LFTS
 
 #endif /* _LIBCPP_STD_VER > 11 */
 
-#endif _LIBCPP_EXPERIMENTAL_RATIO
\ No newline at end of file
+#endif // _LIBCPP_EXPERIMENTAL_RATIO