diff --git a/com.unity.ml-agents/CHANGELOG.md b/com.unity.ml-agents/CHANGELOG.md
index 6c99bc0732..d08bfb0ee3 100755
--- a/com.unity.ml-agents/CHANGELOG.md
+++ b/com.unity.ml-agents/CHANGELOG.md
@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
  - Academy.RegisterSideChannel and UnregisterSideChannel methods were added. (#3391)
  - A tutorial on adding custom SideChannels was added (#3391)
  - Update Barracuda to 0.6.0-preview
+ - The checkpoint file suffix was changed from `.cptk` to `.ckpt` (#3470)
 
 ### Bugfixes
 - Fixed an issue which caused self-play training sessions to consume a lot of memory. (#3451)
diff --git a/ml-agents/mlagents/trainers/tf_policy.py b/ml-agents/mlagents/trainers/tf_policy.py
index bc94320c3a..d51408d5ca 100644
--- a/ml-agents/mlagents/trainers/tf_policy.py
+++ b/ml-agents/mlagents/trainers/tf_policy.py
@@ -309,7 +309,7 @@ def save_model(self, steps):
         :return:
         """
         with self.graph.as_default():
-            last_checkpoint = self.model_path + "/model-" + str(steps) + ".cptk"
+            last_checkpoint = self.model_path + "/model-" + str(steps) + ".ckpt"
             self.saver.save(self.sess, last_checkpoint)
             tf.train.write_graph(
                 self.graph, self.model_path, "raw_graph_def.pb", as_text=False