diff --git a/libavformat/rmdec.c b/libavformat/rmdec.c
index 98e773ca44..96b9e7f238 100644
--- a/libavformat/rmdec.c
+++ b/libavformat/rmdec.c
@@ -969,7 +969,7 @@ static int rm_read_packet(AVFormatContext *s, AVPacket *pkt)
                     st = s->streams[i];
             }
 
-            if(len<0 || avio_feof(s->pb))
+            if (len <= 0 || avio_feof(s->pb))
                 return AVERROR(EIO);
 
             res = ff_rm_parse_packet (s, s->pb, st, st->priv_data, len, pkt,