diff --git a/libavformat/avisynth.c b/libavformat/avisynth.c
index 134b17f1d6..08679e5de7 100644
--- a/libavformat/avisynth.c
+++ b/libavformat/avisynth.c
@@ -19,6 +19,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "libavutil/internal.h"
 #include "avformat.h"
 #include "internal.h"
 #include "riff.h"