diff --git a/libavcodec/h264_refs.c b/libavcodec/h264_refs.c
index af70829594..976044ce2c 100644
--- a/libavcodec/h264_refs.c
+++ b/libavcodec/h264_refs.c
@@ -614,6 +614,12 @@ int ff_h264_execute_ref_pic_marking(H264Context *h)
     int current_ref_assigned = 0, err = 0;
     H264Picture *av_uninit(pic);
 
+    if (!h->ps.sps) {
+        av_log(h->avctx, AV_LOG_ERROR, "SPS is unset\n");
+        err = AVERROR_INVALIDDATA;
+        goto out;
+    }
+
     if (!h->explicit_ref_marking)
         generate_sliding_window_mmcos(h);
     mmco_count = h->nb_mmco;
@@ -817,6 +823,7 @@ int ff_h264_execute_ref_pic_marking(H264Context *h)
             h->frame_recovered |= FRAME_RECOVERED_SEI;
     }
 
+out:
     return (h->avctx->err_recognition & AV_EF_EXPLODE) ? err : 0;
 }