diff --git a/deepxde/nn/pytorch/fnn.py b/deepxde/nn/pytorch/fnn.py
index e07f9581d..b54bef4c6 100644
--- a/deepxde/nn/pytorch/fnn.py
+++ b/deepxde/nn/pytorch/fnn.py
@@ -9,7 +9,9 @@
 class FNN(NN):
     """Fully-connected neural network."""
 
-    def __init__(self, layer_sizes, activation, kernel_initializer, regularization=None):
+    def __init__(
+        self, layer_sizes, activation, kernel_initializer, regularization=None
+    ):
         super().__init__()
         if isinstance(activation, list):
             if not (len(layer_sizes) - 1) == len(activation):
@@ -31,9 +33,10 @@ def __init__(self, layer_sizes, activation, kernel_initializer, regularization=N
             )
             initializer(self.linears[-1].weight)
             initializer_zero(self.linears[-1].bias)
-        self.regularizer=regularization
+        self.regularizer = regularization
         # currently list with two components: regularization type, weight decay
         # currently supports l2 regularization
+
     def forward(self, inputs):
         x = inputs
         if self._input_transform is not None: