diff --git a/libavformat/os_support.h b/libavformat/os_support.h
index 285f039470..de29a18527 100644
--- a/libavformat/os_support.h
+++ b/libavformat/os_support.h
@@ -28,6 +28,7 @@
  */
 
 #ifdef __MINGW32__
+#  define WIN32_LEAN_AND_MEAN
 #  include <windows.h>
 #  define usleep(t)    Sleep((t) / 1000)
 #  include <fcntl.h>