diff --git a/src/HGQ/quantizer/quantizer.py b/src/HGQ/quantizer/quantizer.py
index 82278ca..5387f81 100644
--- a/src/HGQ/quantizer/quantizer.py
+++ b/src/HGQ/quantizer/quantizer.py
@@ -1,9 +1,10 @@
+from collections.abc import Callable
 from functools import singledispatchmethod
 
 import numpy as np
 import tensorflow as tf
 
-from ..utils import L1, L1L2, L2, strategy_dict
+from ..utils import strategy_dict
 
 two = tf.constant(2, dtype=tf.float32)
 log2 = tf.constant(np.log(2), dtype=tf.float32)
@@ -54,7 +55,7 @@ def get_arr_bits(arr: np.ndarray):
 class HGQ:
     """Heterogenous quantizer."""
 
-    def __init__(self, init_bw: float, skip_dims, rnd_strategy: str | int = 'floor', exact_q_value=True, dtype=None, bw_clip=(-23, 23), trainable=True, regularizer=None, minmax_record=False):
+    def __init__(self, init_bw: float, skip_dims, rnd_strategy: str | int = 'floor', exact_q_value=True, dtype=None, bw_clip=(-23, 23), trainable=True, regularizer: Callable | None = None, minmax_record=False):
         self.init_bw = init_bw
         self.skip_dims = skip_dims
         """tuple: Dimensions to use uniform quantizer. If None, use full heterogenous quantizer."""
diff --git a/src/HGQ/utils/__init__.py b/src/HGQ/utils/__init__.py
index c07706e..94b2537 100644
--- a/src/HGQ/utils/__init__.py
+++ b/src/HGQ/utils/__init__.py
@@ -1 +1 @@
-from .utils import L1, L1L2, L2, apf_to_tuple, get_default_kq_conf, get_default_paq_conf, set_default_kq_conf, set_default_paq_conf, strategy_dict, tuple_to_apf, warn
+from .utils import MonoL1, apf_to_tuple, get_default_kq_conf, get_default_paq_conf, set_default_kq_conf, set_default_paq_conf, strategy_dict, tuple_to_apf, warn
diff --git a/src/HGQ/utils/utils.py b/src/HGQ/utils/utils.py
index 08cde05..7902546 100644
--- a/src/HGQ/utils/utils.py
+++ b/src/HGQ/utils/utils.py
@@ -1,11 +1,12 @@
 import re
-import sys
 from warnings import warn as _warn
 
+import keras
 import tensorflow as tf
 
 
-class L1:
+@keras.utils.register_keras_serializable(package='HGQ')
+class MonoL1:
     def __init__(self, l1=0.):
         assert l1 >= 0, f'l1 must be non-negative, got {l1}'
         self.l1 = l1
@@ -17,34 +18,6 @@ def get_config(self):
         return {'l1': self.l1}
 
 
-class L2:
-    def __init__(self, l2=0., zero=-16.):
-        assert l2 >= 0, f'l2 must be non-negative, got {l2}'
-        self.l2 = l2
-        self.zero = zero
-
-    def __call__(self, x):
-        return tf.reduce_sum(tf.square(x - self.zero)) * self.l2
-
-    def get_config(self):
-        return {'l2': self.l2, 'zero': self.zero}
-
-
-class L1L2:
-    def __init__(self, l1=0., l2=0., l2_zero=-16.):
-        assert l1 >= 0, f'l1 must be non-negative, got {l1}'
-        assert l2 >= 0, f'l2 must be non-negative, got {l2}'
-        self.l1 = l1
-        self.l2 = l2
-        self.l2_zero = l2_zero
-
-    def __call__(self, x):
-        return tf.reduce_sum(x) * self.l1 + tf.reduce_sum(tf.square(x - self.l2_zero)) * self.l2
-
-    def get_config(self):
-        return {'l1': self.l1, 'l2': self.l2, 'l2_zero': self.l2_zero}
-
-
 DEFAULT_KERNEL_QUANTIZER_CONFIG = \
     dict(init_bw=2,
          skip_dims=None,
@@ -53,7 +26,7 @@ def get_config(self):
          dtype=None,
          bw_clip=(-23, 23),
          trainable=True,
-         regularizer=L1(1e-6),
+         regularizer=MonoL1(1e-6),
          )
 
 
@@ -65,7 +38,7 @@ def get_config(self):
          dtype=None,
          bw_clip=(-23, 23),
          trainable=True,
-         regularizer=L1(1e-6),
+         regularizer=MonoL1(1e-6),
          minmax_record=True
          )