diff --git a/libcxx/include/ciso646 b/libcxx/include/ciso646
--- a/libcxx/include/ciso646
+++ b/libcxx/include/ciso646
@@ -16,9 +16,10 @@
 */

 #include <__config>
+#include <iso646.h>

 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif

 #endif  // _LIBCPP_CISO646