diff --git a/tensorflow_model_optimization/python/core/quantization/keras/experimental/default_n_bit/default_n_bit_quantize_registry.py b/tensorflow_model_optimization/python/core/quantization/keras/experimental/default_n_bit/default_n_bit_quantize_registry.py
index d33dc67b..b7bf8c56 100644
--- a/tensorflow_model_optimization/python/core/quantization/keras/experimental/default_n_bit/default_n_bit_quantize_registry.py
+++ b/tensorflow_model_optimization/python/core/quantization/keras/experimental/default_n_bit/default_n_bit_quantize_registry.py
@@ -185,9 +185,15 @@ def __init__(self, disable_per_axis=False,
     self._num_bits_activation = num_bits_activation
     self._layer_quantize_map = {}
     for quantize_info in self._LAYER_QUANTIZE_INFO:
-      quantize_info.num_bits_weight = num_bits_weight
-      quantize_info.num_bits_activation = num_bits_activation
-      self._layer_quantize_map[quantize_info.layer_type] = quantize_info
+      new_quantize_info = _QuantizeInfo(
+          layer_type=quantize_info.layer_type,
+          weight_attrs=quantize_info.weight_attrs,
+          activation_attrs=quantize_info.activation_attrs,
+          quantize_output=quantize_info.quantize_output,
+          num_bits_weight=num_bits_weight,
+          num_bits_activation=num_bits_activation,
+      )
+      self._layer_quantize_map[new_quantize_info.layer_type] = new_quantize_info
 
     # Hack for `Activation` layer. That is the only layer with a separate
     # QuantizeConfig.
diff --git a/tensorflow_model_optimization/python/core/quantization/keras/experimental/default_n_bit/default_n_bit_quantize_registry_test.py b/tensorflow_model_optimization/python/core/quantization/keras/experimental/default_n_bit/default_n_bit_quantize_registry_test.py
index 47bd9bc4..a2ed5973 100644
--- a/tensorflow_model_optimization/python/core/quantization/keras/experimental/default_n_bit/default_n_bit_quantize_registry_test.py
+++ b/tensorflow_model_optimization/python/core/quantization/keras/experimental/default_n_bit/default_n_bit_quantize_registry_test.py
@@ -493,7 +493,8 @@ def testSerialization(self):
     quantize_config_from_config = deserialize_keras_object(
         serialized_quantize_config,
         module_objects=globals(),
-        custom_objects=n_bit_registry._types_dict())
+        custom_objects=n_bit_registry._types_dict(),
+    )
 
     self.assertEqual(self.quantize_config, quantize_config_from_config)