diff --git a/fastapi/security/oauth2.py b/fastapi/security/oauth2.py
index 7ee8d83b6..7f65072f6 100644
--- a/fastapi/security/oauth2.py
+++ b/fastapi/security/oauth2.py
@@ -667,7 +667,7 @@ class OAuth2ClientCredentials(OAuth2):
             ),
         ],
         scheme_name: Annotated[
-            Optional[str],
+            str | None,
             Doc(
                 """
                 Security scheme name.
@@ -677,7 +677,7 @@ class OAuth2ClientCredentials(OAuth2):
             ),
         ] = None,
         scopes: Annotated[
-            Optional[Dict[str, str]],
+            dict[str, str] | None,
             Doc(
                 """
                 The OAuth2 scopes that would be required by the *path operations* that
@@ -686,7 +686,7 @@ class OAuth2ClientCredentials(OAuth2):
             ),
         ] = None,
         description: Annotated[
-            Optional[str],
+            str | None,
             Doc(
                 """
                 Security scheme description.
@@ -734,16 +734,12 @@ class OAuth2ClientCredentials(OAuth2):
             auto_error=auto_error,
         )
 
-    async def __call__(self, request: Request) -> Optional[str]:
+    async def __call__(self, request: Request) -> str | None:
         authorization = request.headers.get("Authorization")
         scheme, param = get_authorization_scheme_param(authorization)
         if not authorization or scheme.lower() != "bearer":
             if self.auto_error:
-                raise HTTPException(
-                    status_code=HTTP_401_UNAUTHORIZED,
-                    detail="Not authenticated",
-                    headers={"WWW-Authenticate": "Bearer"},
-                )
+                raise self.make_not_authenticated_error()
             else:
                 return None
         return param
diff --git a/tests/test_security_oauth2_client_credentials.py b/tests/test_security_oauth2_client_credentials.py
index d23a5bc18..1cfc9525c 100644
--- a/tests/test_security_oauth2_client_credentials.py
+++ b/tests/test_security_oauth2_client_credentials.py
@@ -1,4 +1,4 @@
-from typing import Optional
+from typing import Annotated
 
 from fastapi import FastAPI, Security
 from fastapi.security import OAuth2ClientCredentials
@@ -10,7 +10,7 @@ oauth2_scheme = OAuth2ClientCredentials(tokenUrl="token", auto_error=True)
 
 
 @app.get("/items/")
-async def read_items(token: Optional[str] = Security(oauth2_scheme)):
+async def read_items(token: Annotated[str, Security(oauth2_scheme)]):
     return {"token": token}
 
 
diff --git a/tests/test_security_oauth2_client_credentials_optional.py b/tests/test_security_oauth2_client_credentials_optional.py
index f281a61a3..8a748bf1b 100644
--- a/tests/test_security_oauth2_client_credentials_optional.py
+++ b/tests/test_security_oauth2_client_credentials_optional.py
@@ -1,4 +1,4 @@
-from typing import Optional
+from typing import Annotated
 
 from fastapi import FastAPI, Security
 from fastapi.security import OAuth2ClientCredentials
@@ -10,7 +10,7 @@ oauth2_scheme = OAuth2ClientCredentials(tokenUrl="token", auto_error=False)
 
 
 @app.get("/items/")
-async def read_items(token: Optional[str] = Security(oauth2_scheme)):
+async def read_items(token: Annotated[str | None, Security(oauth2_scheme)]):
     return {"token": token}