diff --git a/transip_client/main.py b/transip_client/main.py
index 8f1d2ed..bb85a45 100644
--- a/transip_client/main.py
+++ b/transip_client/main.py
@@ -69,7 +69,9 @@ def _get_domain(domain: str, token: str, api_url: str) -> requests.Response:
     return requests.get(f"{api_url}/domains/{domain}/dns", headers=headers)
 
 
-def _get_domain_data(domains: list[str], token: str, api_url: str) -> Generator[dict]:
+def _get_domain_data(
+    domains: list[str], token: str, api_url: str
+) -> Generator[dict, None, None]:
     with ThreadPoolExecutor(max_workers=10) as executor:
         futures = {
             executor.submit(_get_domain, domain, token, api_url): domain