diff --git a/colossalai/nn/metric/accuracy_2d.py b/colossalai/nn/metric/accuracy_2d.py
index 1137d1963..a86832973 100644
--- a/colossalai/nn/metric/accuracy_2d.py
+++ b/colossalai/nn/metric/accuracy_2d.py
@@ -8,6 +8,7 @@ from ._utils import calc_acc
 class Accuracy2D(nn.Module):
     """Accuracy for 2D parallelism
     """
+
     def __init__(self):
         super().__init__()