diff --git a/contrib/sockets/sockets.lisp b/contrib/sockets/sockets.lisp
index 526d1d737..be71ed8e9 100644
--- a/contrib/sockets/sockets.lisp
+++ b/contrib/sockets/sockets.lisp
@@ -42,7 +42,9 @@
  "#include <netinet/in.h>"
  "#include <errno.h>"
  "#include <fcntl.h>"
- "#include <stdio.h>")
+ "#include <stdio.h>"
+ #+:cygwin
+ "#define MSG_WAITALL 0")
 #+:wsock
 (clines
  "#include <winsock2.h>"
@@ -1260,10 +1262,10 @@ GET-NAME-SERVICE-ERRNO")
 (define-sockopt socket-dont-route "SO_DONTROUTE" bool)
 (define-sockopt socket-linger "SO_LINGER" bool)
 
-#-(or :linux :wsock)
+#-(or :linux :wsock :cygwin)
 (define-sockopt sockopt-reuse-port "SO_REUSEPORT" bool)
 
 ;; Add sockopts here as you need them...
 
 ;; Finished loading
-(provide 'sockets)
\ No newline at end of file
+(provide 'sockets)