Index: include/__config
===================================================================
--- include/__config
+++ include/__config
@@ -713,11 +713,6 @@
 #define _LIBCPP_LOCALE__L_EXTENSIONS 1
 #endif
 
-#if !defined(_WIN32) && !defined(__ANDROID__) && !defined(_NEWLIB_VERSION) && \
-    !defined(__CloudABI__)
-#define _LIBCPP_HAS_CATOPEN 1
-#endif
-
 #ifdef __FreeBSD__
 #define _DECLARE_C99_LDBL_MATH 1
 #endif
Index: include/locale
===================================================================
--- include/locale
+++ include/locale
@@ -199,6 +199,15 @@
 // has had a chance to bake for a bit
 #include <support/newlib/xlocale.h>
 #endif
+
+#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
+// Most unix variants have catopen.  These are the specific ones that don't.
+#if !defined(_WIN32) && !defined(__ANDROID__) && !defined(_NEWLIB_VERSION) && \
+    !defined(__CloudABI__)
+#define _LIBCPP_HAS_CATOPEN 1
+#endif
+#endif
+
 #ifdef _LIBCPP_HAS_CATOPEN
 #include <nl_types.h>
 #endif