diff --git a/comfy/samplers.py b/comfy/samplers.py
index 415a35cc..b12b0fd1 100644
--- a/comfy/samplers.py
+++ b/comfy/samplers.py
@@ -34,7 +34,7 @@ def get_area_and_mult(conds, x_in, timestep_in):
         mask = conds['mask']
         assert(mask.shape[1] == x_in.shape[2])
         assert(mask.shape[2] == x_in.shape[3])
-        mask = mask[:,area[2]:area[0] + area[2],area[3]:area[1] + area[3]] * mask_strength
+        mask = mask[:input_x.shape[0],area[2]:area[0] + area[2],area[3]:area[1] + area[3]] * mask_strength
         mask = mask.unsqueeze(1).repeat(input_x.shape[0] // mask.shape[0], input_x.shape[1], 1, 1)
     else:
         mask = torch.ones_like(input_x)