diff --git a/inference_mp4_2x.py b/inference_mp4_2x.py
index e7ccaeb..9df0dbd 100644
--- a/inference_mp4_2x.py
+++ b/inference_mp4_2x.py
@@ -47,13 +47,13 @@ while success:
             mid = model.inference(I0, I1)
             mid = ((mid[0].cpu().detach().numpy().transpose(1, 2, 0))*255.).astype('uint8')
         if args.montage:
-            output.write(torch.cat((lastframe, lastframe), 2))
-            output.write(torch.cat((lastframe, mid[:h, :w]), 2))
+            output.write(np.concatenate((lastframe, lastframe), 1))
+            output.write(np.concatenate((lastframe, mid[:h, :w]), 1))
         else:
             output.write(lastframe)
             output.write(mid[:h, :w])
     if args.montage:
-        output.write(torch.cat((frame, frame), 2))
+        output.write(np.concatenate((frame, frame), 1))
     else:
         output.write(frame)
 output.release()