diff --git a/wan/image2video.py b/wan/image2video.py
index 6882c53..17849b2 100644
--- a/wan/image2video.py
+++ b/wan/image2video.py
@@ -207,7 +207,7 @@ class WanI2V:
             generator=seed_g,
             device=self.device)
 
-        msk = torch.ones(1, 81, lat_h, lat_w, device=self.device)
+        msk = torch.ones(1, frame_num, lat_h, lat_w, device=self.device)
         msk[:, 1:] = 0
         msk = torch.concat([
             torch.repeat_interleave(msk[:, 0:1], repeats=4, dim=1), msk[:, 1:]