diff --git a/lib/curl_memory.h b/lib/curl_memory.h
index 0faf928617..df64786e8a 100644
--- a/lib/curl_memory.h
+++ b/lib/curl_memory.h
@@ -79,6 +79,9 @@
 
 #undef socket
 #undef accept
+#ifdef HAVE_ACCEPT4
+#undef accept4
+#endif
 #ifdef HAVE_SOCKETPAIR
 #undef socketpair
 #endif