diff --git a/libavformat/amr.c b/libavformat/amr.c
index 76136e626b..260bd6ada6 100644
--- a/libavformat/amr.c
+++ b/libavformat/amr.c
@@ -181,6 +181,7 @@ AVInputFormat ff_amr_demuxer = {
     amr_read_header,
     amr_read_packet,
     NULL,
+    .flags = AVFMT_GENERIC_INDEX,
 };
 #endif