diff --git a/aiohttp_apispec/aiohttp_apispec.py b/aiohttp_apispec/aiohttp_apispec.py
index 4058053..e96e5bd 100644
--- a/aiohttp_apispec/aiohttp_apispec.py
+++ b/aiohttp_apispec/aiohttp_apispec.py
@@ -248,7 +248,7 @@ def setup_aiohttp_apispec(
     prefix: str = '',
     schema_name_resolver: Callable = resolver,
     **kwargs,
-) -> None:
+) -> AiohttpApiSpec:
     """
     aiohttp-apispec extension.