diff --git a/pyslack/__init__.py b/pyslack/__init__.py
index dabee5c..e10565e 100644
--- a/pyslack/__init__.py
+++ b/pyslack/__init__.py
@@ -58,25 +58,23 @@ def chat_post_message(self, channel, text, **params):
         })
         return self._make_request(method, params)
 
-    def chat_update_message(self, channel, text, timestamp, **params):
+    def chat_update_message(self, channel, text, timestamp):
         """chat.update
+        https://api.slack.com/methods/chat.update
 
         This method updates a message.
 
-        Check docs for all available **params options:
-        https://api.slack.com/methods/chat.update
-
         Required parameters:
         `ts`:  Timestamp of the message to be updated (e.g: "1405894322.002768")    
         `channel`: Channel containing the message to be updated. (e.g: "C1234567890")
         `text`: New text for the message, using the default formatting rules. (e.g: "Hello world")
         """
         method = 'chat.update'
-        params.update({
+        params = {
             'channel': channel,
             'text': text,
             'ts': timestamp,
-        })
+        }
         return self._make_request(method, params)