diff --git a/libavformat/iff.c b/libavformat/iff.c
index 1efc1472cc..edf308b135 100644
--- a/libavformat/iff.c
+++ b/libavformat/iff.c
@@ -481,5 +481,5 @@ AVInputFormat ff_iff_demuxer = {
     .read_probe     = iff_probe,
     .read_header    = iff_read_header,
     .read_packet    = iff_read_packet,
-    .flags          = AVFMT_GENERIC_INDEX,
+    .flags          = AVFMT_GENERIC_INDEX | AVFMT_NO_BYTE_SEEK,
 };