diff --git a/timm/models/layers/blurpool.py b/timm/models/layers/blurpool.py
index 6df2b748..57af3e0e 100644
--- a/timm/models/layers/blurpool.py
+++ b/timm/models/layers/blurpool.py
@@ -49,7 +49,7 @@ class BlurPool2d(nn.Module):
         self.blur_filter = fn(self.blur_filter)
 
     def forward(self, input_tensor: torch.Tensor) -> torch.Tensor:  # type: ignore
+        C = input_tensor.shape[1]
         return F.conv2d(
             self.padding(input_tensor),
-            self.blur_filter.type(input_tensor.dtype).expand(C, -1, -1, -1),
-            stride=self.stride, groups=input_tensor.shape[1])
+            self.blur_filter.type(input_tensor.dtype).expand(C, -1, -1, -1), stride=self.stride, groups=C)