diff --git a/libavfilter/vf_thumbnail.c b/libavfilter/vf_thumbnail.c
index fe4a086493..0b7ba06482 100644
--- a/libavfilter/vf_thumbnail.c
+++ b/libavfilter/vf_thumbnail.c
@@ -176,11 +176,11 @@ static int request_frame(AVFilterLink *link)
 
     /* loop until a frame thumbnail is available (when a frame is queued,
      * thumb->n is reset to zero) */
-    while (thumb->n) {
+    do {
         int ret = avfilter_request_frame(link->src->inputs[0]);
         if (ret < 0)
             return ret;
-    }
+    } while (thumb->n);
     return 0;
 }