diff --git a/telethon/client/telegrambaseclient.py b/telethon/client/telegrambaseclient.py
index d3abbc3c..b0882e6c 100644
--- a/telethon/client/telegrambaseclient.py
+++ b/telethon/client/telegrambaseclient.py
@@ -118,7 +118,7 @@ class TelegramBaseClient(abc.ABC):
 
         flood_sleep_threshold (`int` | `float`, optional):
             The threshold below which the library should automatically
-            sleep on flood wait errors (inclusive). For instance, if a
+            sleep on flood wait and slow mode wait errors (inclusive). For instance, if a
             ``FloodWaitError`` for 17s occurs and `flood_sleep_threshold`
             is 20s, the library will ``sleep`` automatically. If the error
             was for 21s, it would ``raise FloodWaitError`` instead. Values
diff --git a/telethon/client/users.py b/telethon/client/users.py
index 685f6134..15fcf771 100644
--- a/telethon/client/users.py
+++ b/telethon/client/users.py
@@ -82,7 +82,7 @@ class UserMethods:
                     e.__class__.__name__, e)
 
                 await asyncio.sleep(2)
-            except (errors.FloodWaitError, errors.FloodTestPhoneWaitError) as e:
+            except (errors.FloodWaitError, errors.SlowModeWaitError, errors.FloodTestPhoneWaitError) as e:
                 if utils.is_list_like(request):
                     request = request[request_index]
 
diff --git a/telethon_generator/data/errors.csv b/telethon_generator/data/errors.csv
index aab5bddd..38ef5816 100644
--- a/telethon_generator/data/errors.csv
+++ b/telethon_generator/data/errors.csv
@@ -228,6 +228,7 @@ SESSION_PASSWORD_NEEDED,401,Two-steps verification is enabled and a password is
 SESSION_REVOKED,401,"The authorization has been invalidated, because of the user terminating all sessions"
 SHA256_HASH_INVALID,400,The provided SHA256 hash is invalid
 SHORTNAME_OCCUPY_FAILED,400,An error occurred when trying to register the short-name used for the sticker pack. Try a different name
+SLOWMODE_WAIT_X,420,A wait of {seconds} seconds is required before sending another message in this chat
 START_PARAM_EMPTY,400,The start parameter is empty
 START_PARAM_INVALID,400,Start parameter invalid
 STICKERSET_INVALID,400,The provided sticker set is invalid
diff --git a/telethon_generator/parsers/errors.py b/telethon_generator/parsers/errors.py
index 4fb9d43d..df352999 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: