diff --git a/telethon_generator/parsers/errors.py b/telethon_generator/parsers/errors.py
index 4fb9d43d..45ad27c7 100644
--- a/telethon_generator/parsers/errors.py
+++ b/telethon_generator/parsers/errors.py
@@ -28,7 +28,8 @@ def _get_class_name(error_code):
         )
 
     return snake_to_camel_case(
-        error_code.replace('FIRSTNAME', 'FIRST_NAME').lower(), suffix='Error')
+        error_code.replace('FIRSTNAME', 'FIRST_NAME')\
+        .replace('SLOWMODE', 'SLOW_MODE').lower(), suffix='Error')
 
 
 class Error: