diff --git a/mmdet/models/mask_heads/fcn_mask_head.py b/mmdet/models/mask_heads/fcn_mask_head.py
index 7c440dc3770b5df53f6b327ee53261b8fc55eb3f..6578e8cf4e8e94d860170b4409b1c2b9a5e3a19c 100644
--- a/mmdet/models/mask_heads/fcn_mask_head.py
+++ b/mmdet/models/mask_heads/fcn_mask_head.py
@@ -49,7 +49,7 @@ class FCNMaskHead(nn.Module):
                 ConvModule(
                     in_channels,
                     self.conv_out_channels,
-                    3,
+                    self.conv_kernel_size,
                     padding=padding,
                     normalize=normalize,
                     bias=self.with_bias))