diff --git a/telegram/callbackquery.py b/telegram/callbackquery.py
index cd4feace2..c461a4072 100644
--- a/telegram/callbackquery.py
+++ b/telegram/callbackquery.py
@@ -34,7 +34,7 @@ class CallbackQuery(TelegramObject):
         self.message = kwargs.get('message')
         self.data = kwargs.get('data', '')
         self.inline_message_id = kwargs.get('inline_message_id', '')
-        self.game_short_name = kwargs.get('game_short_name')
+        self.game_short_name = kwargs.get('game_short_name', '')
 
         self.bot = bot
 
diff --git a/telegram/chat.py b/telegram/chat.py
index 3bd0e9b6c..91af15ba9 100644
--- a/telegram/chat.py
+++ b/telegram/chat.py
@@ -58,7 +58,7 @@ class Chat(TelegramObject):
         self.username = kwargs.get('username', '')
         self.first_name = kwargs.get('first_name', '')
         self.last_name = kwargs.get('last_name', '')
-        self.all_members_are_admins = kwargs.get('all_members_are_admins', '')
+        self.all_members_are_admins = kwargs.get('all_members_are_admins', False)
 
         self.bot = bot
 
diff --git a/telegram/game.py b/telegram/game.py
index 5b30e374d..602ca031d 100644
--- a/telegram/game.py
+++ b/telegram/game.py
@@ -48,7 +48,7 @@ class Game(TelegramObject):
                  title,
                  description,
                  photo,
-                 text=None,
+                 text='',
                  text_entities=None,
                  animation=None,
                  **kwargs):
diff --git a/telegram/webhookinfo.py b/telegram/webhookinfo.py
index 8b6cd07f7..f96bb01aa 100644
--- a/telegram/webhookinfo.py
+++ b/telegram/webhookinfo.py
@@ -45,8 +45,8 @@ class WebhookInfo(TelegramObject):
         self.url = url
         self.has_custom_certificate = has_custom_certificate
         self.pending_update_count = pending_update_count
-        self.last_error_date = kwargs.get('last_error_date')
-        self.last_error_message = kwargs.get('last_error_message')
+        self.last_error_date = kwargs.get('last_error_date', '')
+        self.last_error_message = kwargs.get('last_error_message', '')
 
     @staticmethod
     def de_json(data, bot):