diff --git a/libavformat/network.h b/libavformat/network.h
index 6943bc6765..84a8f539d9 100644
--- a/libavformat/network.h
+++ b/libavformat/network.h
@@ -22,6 +22,7 @@
 #define AVFORMAT_NETWORK_H
 
 #include "config.h"
+#include "os_support.h"
 
 #if HAVE_WINSOCK2_H
 #include <winsock2.h>