diff --git a/docker_registry_client_async/dockerregistryclientasync.py b/docker_registry_client_async/dockerregistryclientasync.py
index f2d4db3..86f809c 100644
--- a/docker_registry_client_async/dockerregistryclientasync.py
+++ b/docker_registry_client_async/dockerregistryclientasync.py
@@ -278,9 +278,13 @@ async def _get_auth_token(
         headers = {}
         if credentials:
             headers["Authorization"] = f"Basic {credentials}"
-        url = GENERIC_OAUTH2_URL_PATTERN.format(
-            bearer["realm"], bearer["service"], scope
-        )
+        if "service" not in bearer:
+            oauth2_url_pattern_without_service = "{0}?scope={1}&client_id=docker-registry-client-async"
+            url = oauth2_url_pattern_without_service.format(bearer["realm"], scope)
+        else:
+            url = GENERIC_OAUTH2_URL_PATTERN.format(
+                bearer["realm"], bearer["service"], scope
+            )
         client_response = await client_session.get(
             headers=headers,
             raise_for_status=True,