diff --git a/vio/viosocket.c b/vio/viosocket.c
index c969a14..c3d9266 100644
--- a/vio/viosocket.c
+++ b/vio/viosocket.c
@@ -29,6 +29,7 @@
   #pragma comment(lib, "ws2_32.lib")
 #endif
 #include "vio_priv.h"
+#include <netinet/tcp.h>