diff --git a/compiler_opt/rl/gin_external_configurables.py b/compiler_opt/rl/gin_external_configurables.py
index 34ae60d2..c2593092 100644
--- a/compiler_opt/rl/gin_external_configurables.py
+++ b/compiler_opt/rl/gin_external_configurables.py
@@ -26,7 +26,6 @@
 # Activation function.
 config.external_configurable(tf.keras.activations.relu,
                              'tf.keras.activations.relu')
-config.external_configurable(tf.nn.relu6, 'tf.nn.relu6')
 
 # Layers
 config.external_configurable(tf.keras.layers.Add, 'tf.keras.layers.Add')