-#if !HAVE_INET_NTOP /* not already defined and declared in <arpa/inet.h> ? */
-extern const char *inet_ntop(int af, const void *src, char *dst, socklen_t cnt);
+#if !HAVE_DECL_INET_NTOP
+extern const char *inet_ntop (int af, const void *restrict src,
+ char *restrict dst, socklen_t cnt);