diff --git a/libavcodec/mpegvideo_motion.c b/libavcodec/mpegvideo_motion.c
index be1b48d4d8a5ad07fc16aa30d2de4cf07b6c9be9..225e9a637f59283027e403d8539fda230a0aa3ee 100644
--- a/libavcodec/mpegvideo_motion.c
+++ b/libavcodec/mpegvideo_motion.c
@@ -809,7 +809,8 @@ static av_always_inline void MPV_motion_internal(MpegEncContext *s,
                                   s->mv[dir][1][0], s->mv[dir][1][1], 8, mb_y);
             }
         } else {
-            if(s->picture_structure != s->field_select[dir][0] + 1 && s->pict_type != AV_PICTURE_TYPE_B && !s->first_field){
+            if(   s->picture_structure != s->field_select[dir][0] + 1 && s->pict_type != AV_PICTURE_TYPE_B && !s->first_field
+               || !ref_picture[0]){
                 ref_picture = s->current_picture_ptr->f.data;
             }