diff --git a/12_custom_models_and_training_with_tensorflow.ipynb b/12_custom_models_and_training_with_tensorflow.ipynb
index 887c5c7..3dec28f 100644
--- a/12_custom_models_and_training_with_tensorflow.ipynb
+++ b/12_custom_models_and_training_with_tensorflow.ipynb
@@ -1803,8 +1803,6 @@
     "        self.stddev = stddev\n",
     "\n",
     "    def call(self, X, training=None):\n",
-    "        if training is None:\n",
-    "            training = keras.backend.learning_phase()\n",
     "        if training:\n",
     "            noise = tf.random.normal(tf.shape(X), stddev=self.stddev)\n",
     "            return X + noise\n",
@@ -1990,8 +1988,6 @@
     "\n",
     "    @tf.function\n",
     "    def call(self, inputs, training=None):\n",
-    "        if training is None:\n",
-    "            training = keras.backend.learning_phase()\n",
     "        Z = inputs\n",
     "        for layer in self.hidden:\n",
     "            Z = layer(Z)\n",