diff --git a/libavcodec/mpegvideo.c b/libavcodec/mpegvideo.c
index 00ced1f926..6ace50143f 100644
--- a/libavcodec/mpegvideo.c
+++ b/libavcodec/mpegvideo.c
@@ -1593,7 +1593,10 @@ int ff_MPV_frame_start(MpegEncContext *s, AVCodecContext *avctx)
         int h_chroma_shift, v_chroma_shift;
         av_pix_fmt_get_chroma_sub_sample(s->avctx->pix_fmt,
                                          &h_chroma_shift, &v_chroma_shift);
-        if (s->pict_type != AV_PICTURE_TYPE_I)
+        if (s->pict_type == AV_PICTURE_TYPE_B && s->next_picture_ptr && s->next_picture_ptr->f.data[0])
+            av_log(avctx, AV_LOG_INFO,
+                   "allocating dummy last picture for B frame\n");
+        else if (s->pict_type != AV_PICTURE_TYPE_I)
             av_log(avctx, AV_LOG_ERROR,
                    "warning: first frame is no keyframe\n");
         else if (s->picture_structure != PICT_FRAME)