diff --git a/libavformat/mm.c b/libavformat/mm.c
index 8a1382e03c..de5f9d6161 100644
--- a/libavformat/mm.c
+++ b/libavformat/mm.c
@@ -174,6 +174,8 @@ static int read_packet(AVFormatContext *s,
             return 0;
 
         case MM_TYPE_AUDIO :
+            if (s->nb_streams < 2)
+                return AVERROR_INVALIDDATA;
             if (av_get_packet(s->pb, pkt, length)<0)
                 return AVERROR(ENOMEM);
             pkt->stream_index = 1;