diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index 78a3ec6b06..852fb7e056 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -3031,6 +3031,7 @@ static int mxf_parse_structural_metadata(MXFContext *mxf)
             if (container_ul->desc)
                 av_dict_set(&st->metadata, "data_type", container_ul->desc, 0);
             if (mxf->eia608_extract &&
+                container_ul->desc &&
                 !strcmp(container_ul->desc, "vbi_vanc_smpte_436M")) {
                 st->codecpar->codec_type = AVMEDIA_TYPE_SUBTITLE;
                 st->codecpar->codec_id = AV_CODEC_ID_EIA_608;