diff --git a/libav/raw.c b/libav/raw.c
index 6cfa268e13f56db8c0ec260eae4d8942ce026b21..1d52dded78c65ef6d440a2ac0c16f2ad3e332aed 100644
--- a/libav/raw.c
+++ b/libav/raw.c
@@ -244,10 +244,11 @@ AVInputFormat m4v_iformat = {
     "m4v",
     "raw MPEG4 video format",
     0,
-    mpegvideo_probe,
+    NULL /*mpegvideo_probe*/,
     video_read_header,
     raw_read_packet,
     raw_read_close,
+    extensions: "m4v", //FIXME remove after writing mpeg4_probe
     value: CODEC_ID_MPEG4,
 };