diff --git a/deepmd/tf/fit/polar.py b/deepmd/tf/fit/polar.py
index ee33feb0af..8b4eebc9da 100644
--- a/deepmd/tf/fit/polar.py
+++ b/deepmd/tf/fit/polar.py
@@ -466,7 +466,9 @@ def build(
                 # nframes x nloc_masked
                 constant_matrix = tf.reshape(
                     tf.reshape(
-                        tf.tile(tf.repeat(self.t_bias_atom_polar, natoms[2:]), [nframes]),
+                        tf.tile(
+                            tf.repeat(self.t_bias_atom_polar, natoms[2:]), [nframes]
+                        ),
                         [nframes, -1],
                     )[nloc_mask],
                     [nframes, -1],
@@ -518,7 +520,9 @@ def build(
                 # shift and scale
                 sel_type_idx = self.sel_type.index(type_i)
                 final_layer = final_layer * self.scale[sel_type_idx]
-                final_layer = final_layer + tf.slice(self.t_bias_atom_polar, [sel_type_idx], [1]) * tf.eye(
+                final_layer = final_layer + tf.slice(
+                    self.t_bias_atom_polar, [sel_type_idx], [1]
+                ) * tf.eye(
                     3,
                     batch_shape=[tf.shape(inputs)[0], natoms[2 + type_i]],
                     dtype=GLOBAL_TF_FLOAT_PRECISION,