diff --git a/libavformat/iamfdec.c b/libavformat/iamfdec.c
index ce6d4aa064..2e6608b868 100644
--- a/libavformat/iamfdec.c
+++ b/libavformat/iamfdec.c
@@ -107,7 +107,7 @@ static int iamf_read_header(AVFormatContext *s)
             if (ret < 0)
                 return ret;
 
-            if (!i && !j && audio_element->layers[0].substream_count == 1)
+            if (!i && !j && audio_element->nb_layers && audio_element->layers[0].substream_count == 1)
                 st->disposition |= AV_DISPOSITION_DEFAULT;
             else
                 st->disposition |= AV_DISPOSITION_DEPENDENT;