diff --git a/tensorflow/contrib/layers/python/layers/optimizers.py b/tensorflow/contrib/layers/python/layers/optimizers.py
index 8c06202f47b..6cb7e91b73f 100644
--- a/tensorflow/contrib/layers/python/layers/optimizers.py
+++ b/tensorflow/contrib/layers/python/layers/optimizers.py
@@ -258,10 +258,11 @@ def optimize_loss(loss,
         grad_values = gradient
 
       if grad_values is not None:
+        var_name = variable.name.replace(":", "_")
         if "gradients" in summaries:
-          summary.histogram("gradients/" + variable.name, grad_values)
+          summary.histogram("gradients/%s" % var_name, grad_values)
         if "gradient_norm" in summaries:
-          summary.scalar("gradient_norm/" + variable.name,
+          summary.scalar("gradient_norm/%s" % var_name,
                          clip_ops.global_norm([grad_values]))
 
     if clip_gradients is not None and "gradient_norm" in summaries:
diff --git a/tensorflow/python/summary/summary.py b/tensorflow/python/summary/summary.py
index a6b348cc991..b5db6b802fa 100644
--- a/tensorflow/python/summary/summary.py
+++ b/tensorflow/python/summary/summary.py
@@ -35,8 +35,6 @@ from __future__ import print_function
 
 import re as _re
 
-import six
-
 from google.protobuf import json_format as _json_format
 from tensorflow.core.framework import summary_pb2 as _summary_pb2
 from tensorflow.python.framework import dtypes as _dtypes
@@ -47,8 +45,8 @@ from tensorflow.python.ops import gen_logging_ops as _gen_logging_ops
 from tensorflow.python.ops.summary_ops import tensor_summary
 # pylint: enable=unused-import
 from tensorflow.python.platform import tf_logging as _logging
-from tensorflow.python.util.all_util import remove_undocumented
 from tensorflow.python.util import compat as _compat
+from tensorflow.python.util.all_util import remove_undocumented
 
 
 def _collect(val, collections, default_collections):
@@ -60,6 +58,7 @@ def _collect(val, collections, default_collections):
 
 _INVALID_TAG_CHARACTERS = _re.compile(r'[^-/\w\.]')
 
+
 def _clean_tag(name):
   # In the past, the first argument to summary ops was a tag, which allowed
   # arbitrary characters. Now we are changing the first argument to be the node