diff --git a/stubs/html5lib/METADATA.toml b/stubs/html5lib/METADATA.toml
index 23a4684130a6..6e34b51f685f 100644
--- a/stubs/html5lib/METADATA.toml
+++ b/stubs/html5lib/METADATA.toml
@@ -1,5 +1,7 @@
 version = "1.1.*"
 upstream_repository = "https://github.com/html5lib/html5lib-python"
 
+requires = ["six"]
+
 [tool.stubtest]
 extras = ["all"]
diff --git a/stubs/html5lib/html5lib/serializer.pyi b/stubs/html5lib/html5lib/serializer.pyi
index e7232e2e1d11..834e2c21a376 100644
--- a/stubs/html5lib/html5lib/serializer.pyi
+++ b/stubs/html5lib/html5lib/serializer.pyi
@@ -1,7 +1,8 @@
 from _typeshed import Incomplete
-from collections.abc import Generator
 from typing import overload
 
+from six import text_type
+
 k: str
 v: str | int
 
@@ -32,11 +33,11 @@ class HTMLSerializer:
     errors: Incomplete
     strict: bool
     def __init__(self, **kwargs) -> None: ...
-    def encode(self, string): ...
-    def encodeStrict(self, string): ...
+    def encode(self, string: text_type) -> str: ...
+    def encodeStrict(self, string: text_type) -> str: ...
     encoding: Incomplete
-    def serialize(self, treewalker, encoding=None) -> Generator[Incomplete]: ...
-    def render(self, treewalker, encoding=None): ...
+    def serialize(self, treewalker: str, encoding: str) -> str: ...
+    def render(self, treewalker: str, encoding: str) -> str: ...
     def serializeError(self, data: str = "XXX ERROR MESSAGE NEEDED") -> None: ...
 
 class SerializeError(Exception): ...