diff --git a/telethon/errors/rpc_errors.py b/telethon/errors/rpc_errors.py
index 55d03ff3..5c938641 100644
--- a/telethon/errors/rpc_errors.py
+++ b/telethon/errors/rpc_errors.py
@@ -38,6 +38,10 @@ class ForbiddenError(RPCError):
     code = 403
     message = 'FORBIDDEN'
 
+    def __init__(self, message):
+        super().__init__(self, message)
+        self.message = message
+
 
 class NotFoundError(RPCError):
     """
@@ -46,6 +50,10 @@ class NotFoundError(RPCError):
     code = 404
     message = 'NOT_FOUND'
 
+    def __init__(self, message):
+        super().__init__(self, message)
+        self.message = message
+
 
 class FloodError(RPCError):
     """
@@ -67,6 +75,10 @@ class ServerError(RPCError):
     code = 500
     message = 'INTERNAL'
 
+    def __init__(self, message):
+        super().__init__(self, message)
+        self.message = message
+
 
 class BadMessageError(Exception):
     """Occurs when handling a bad_message_notification"""