diff --git a/libavfilter/vsrc_mptestsrc.c b/libavfilter/vsrc_mptestsrc.c
index 03073dcf5a..55b723af00 100644
--- a/libavfilter/vsrc_mptestsrc.c
+++ b/libavfilter/vsrc_mptestsrc.c
@@ -308,6 +308,7 @@ static int request_frame(AVFilterLink *outlink)
     if (!picref)
         return AVERROR(ENOMEM);
     picref->pts = test->pts++;
+    picref->duration = 1;
 
     // clean image
     for (i = 0; i < h; i++)