diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index a093b0806a..822a20f6ce 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -3911,6 +3911,11 @@ static int decode_slice_header(H264Context *h, H264Context *h0){
     h->slice_type= slice_type;
 
     s->pict_type= h->slice_type; // to make a few old func happy, it's wrong though
+    if (s->pict_type == B_TYPE && s->last_picture_ptr == NULL) {
+        av_log(h->s.avctx, AV_LOG_ERROR,
+               "B picture before any references, skipping\n");
+        return -1;
+    }
 
     pps_id= get_ue_golomb(&s->gb);
     if(pps_id>=MAX_PPS_COUNT){