diff --git a/libavformat/mov.c b/libavformat/mov.c
index be602ee652..8dc60624c1 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -1010,6 +1010,7 @@ static int mov_read_extradata(MOVContext *c, AVIOContext *pb, MOVAtom atom,
         av_log(c->fc, AV_LOG_WARNING, "truncated extradata\n");
         st->codec->extradata_size -= atom.size - err;
     }
+    memset(buf + 8 + err, 0, FF_INPUT_BUFFER_PADDING_SIZE);
     return 0;
 }