#define YESEXPR 52 /* affirmative response expression */
#define NOEXPR 53 /* negative response expression */
-#if !defined(_ANSI_SOURCE)
+#if (__DARWIN_C_LEVEL > __DARWIN_C_ANSI && __DARWIN_C_LEVEL < 200112L) || __DARWIN_C_LEVEL == __DARWIN_C_FULL
#define YESSTR 54 /* affirmative response for yes/no queries */
#define NOSTR 55 /* negative response for yes/no queries */
#endif