diff --git a/libavformat/rtspenc.c b/libavformat/rtspenc.c
index 88f093f5c1..d54be1a5c2 100644
--- a/libavformat/rtspenc.c
+++ b/libavformat/rtspenc.c
@@ -26,6 +26,7 @@
 #include <poll.h>
 #endif
 #include "network.h"
+#include "os_support.h"
 #include "rtsp.h"
 #include "internal.h"
 #include "libavutil/intreadwrite.h"