diff --git a/mastodon/Mastodon.py b/mastodon/Mastodon.py
index 393d021..0d1750f 100644
--- a/mastodon/Mastodon.py
+++ b/mastodon/Mastodon.py
@@ -2107,7 +2107,8 @@ class Mastodon:
     def account_update_credentials(self, display_name=None, note=None,
                                    avatar=None, avatar_mime_type=None,
                                    header=None, header_mime_type=None, 
-                                   locked=None, fields=None):
+                                   locked=None, bot=None, 
+                                   discoverable=None, fields=None):
         """
         Update the profile for the currently logged-in user.
 
@@ -2118,6 +2119,8 @@ class Mastodon:
         
         'locked' specifies whether the user needs to manually approve follow requests.
         
+        'bot' specifies whether the user should be set to a bot.
+        
         'fields' can be a list of up to four name-value pairs (specified as tuples) to 
         appear as semi-structured information in the users profile.
         
@@ -2136,7 +2139,7 @@ class Mastodon:
         
         # Load header, if specified
         if not header is None:
-            if header_mime_type is None and (isinstance(avatar, str) and os.path.isfile(header)):
+            if header_mime_type is None and (isinstance(header, str) and os.path.isfile(header)):
                 header_mime_type = guess_type(header)
                 header = open(header, 'rb')