diff --git a/python/google/protobuf/message.py b/python/google/protobuf/message.py
index 0fe6a4f93c..786c09f186 100755
--- a/python/google/protobuf/message.py
+++ b/python/google/protobuf/message.py
@@ -192,7 +192,7 @@ class Message(object):
     raise NotImplementedError
 
   def ParseFromString(self, serialized):
-    """Parse serialized protocol buffer data into this message.
+    """Parse serialized protocol buffer data in binary form into this message.
 
     Like :func:`MergeFromString()`, except we clear the object first.