diff --git a/libavformat/mxg.c b/libavformat/mxg.c
index 6a39873f21..40139d7d3d 100644
--- a/libavformat/mxg.c
+++ b/libavformat/mxg.c
@@ -127,6 +127,8 @@ static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
 
     mxg->cache_size += ret;
 
+    memset(mxg->buffer_ptr + mxg->cache_size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
+
     return ret;
 }