diff --git a/libavfilter/vf_overlay_qsv.c b/libavfilter/vf_overlay_qsv.c
index 20871786ee..9aabb594ba 100644
--- a/libavfilter/vf_overlay_qsv.c
+++ b/libavfilter/vf_overlay_qsv.c
@@ -160,7 +160,7 @@ release:
 
 static int have_alpha_planar(AVFilterLink *link)
 {
-    enum AVPixelFormat pix_fmt;
+    enum AVPixelFormat pix_fmt = link->format;
     const AVPixFmtDescriptor *desc;
     AVHWFramesContext *fctx;