diff --git a/tensorflow/python/distribute/cross_device_utils.py b/tensorflow/python/distribute/cross_device_utils.py
index febdc2ae556..8813dad4952 100644
--- a/tensorflow/python/distribute/cross_device_utils.py
+++ b/tensorflow/python/distribute/cross_device_utils.py
@@ -35,6 +35,9 @@ from tensorflow.python.ops import math_ops
 from tensorflow.python.ops import nccl_ops
 
 
+OP_INSTANCE_KEY_START_NUMBER = 100
+
+
 def aggregate_gradients_using_nccl(replica_grads):
   """Aggregate gradients using nccl allreduce."""
   agg_all_g_and_v = []
@@ -253,7 +256,7 @@ class CollectiveKeys(object):
 
   def __init__(self,
                group_key_start=1,
-               op_instance_key_start=100,
+               op_instance_key_start=OP_INSTANCE_KEY_START_NUMBER,
                variable_instance_key_start=1000000):
     """Initializes the object.