--- Libc/Libc-391/include/standards.h
+++ Libc/Libc-583/include/standards.h
@@ -27,11 +27,13 @@
 #ifndef _STANDARDS_H
 #define _STANDARDS_H
 
-#ifdef _POSIX_C_SOURCE
+#include <sys/cdefs.h>
+
+#if defined(_POSIX_C_SOURCE) && !defined(_DARWIN_C_SOURCE)
 #        ifndef __STRICT_ANSI__
 #                define __STRICT_ANSI__
 #        endif
 #        undef __STRICT_BSD__
-#endif /* _POSIX_C_SOURCE */
+#endif /* (_POSIX_C_SOURCE && !_DARWIN_C_SOURCE) */
 
 #endif /* _STANDARDS_H */