diff --git a/contrib/sockets/sockets.lisp b/contrib/sockets/sockets.lisp
index 7ab881769..8f96ca6d7 100755
--- a/contrib/sockets/sockets.lisp
+++ b/contrib/sockets/sockets.lisp
@@ -68,6 +68,10 @@
  "#include <fcntl.h>"
  "#include <stdio.h>")
 
+#+windows
+(clines
+ "#include <ws2tcpip.h>")
+
 #+:wsock
 (progn
   (defvar +wsock-initialized+ nil)