diff --git a/telegram/bot.py b/telegram/bot.py
index fb50b055d..24d2c31b5 100644
--- a/telegram/bot.py
+++ b/telegram/bot.py
@@ -1975,7 +1975,7 @@ class Bot(TelegramObject):
         data = {'shipping_query_id': shipping_query_id, 'ok': ok}
 
         if ok is True:
-            data['shipping_options'] = shipping_options
+            data['shipping_options'] = [option.to_dict() for option in shipping_options]
         if error_message is not None:
             data['error_message'] = error_message
 
@@ -2009,7 +2009,7 @@ class Bot(TelegramObject):
 
         """
 
-        if not (ok ^ (error_message is None)):
+        if not (ok ^ (error_message is not None)):
             raise TelegramError(
                 'answerPreCheckoutQuery: If ok is True, there should '
                 'not be error_message; if ok is False, error_message '