diff --git a/libavfilter/vf_yadif.c b/libavfilter/vf_yadif.c
index 04b03ada53..2494232033 100644
--- a/libavfilter/vf_yadif.c
+++ b/libavfilter/vf_yadif.c
@@ -274,7 +274,7 @@ static int poll_frame(AVFilterLink *link)
             return ret;
         val = avfilter_poll_frame(link->src->inputs[0]);
     }
-    assert(yadif->next);
+    assert(yadif->next || !val);
 
     return val * ((yadif->mode&1)+1);
 }