diff --git a/src/dials_rest/auth.py b/src/dials_rest/auth.py
index 52083d2..50d0a81 100644
--- a/src/dials_rest/auth.py
+++ b/src/dials_rest/auth.py
@@ -52,7 +52,14 @@ def __init__(self, auto_error: bool = True):
         super().__init__(auto_error=auto_error)
 
     async def __call__(self, request: Request) -> UserToken:
-        token: HTTPAuthorizationCredentials = await super().__call__(request)
+        try:
+            token: HTTPAuthorizationCredentials = await super().__call__(request)
+        except HTTPException as exception:
+            # Convert HTTP_403_FORBIDDEN to HTTP_401_UNAUTHORIZED
+            # See https://github.com/tiangolo/fastapi/discussions/9130
+            raise HTTPException(
+                status_code=status.HTTP_401_UNAUTHORIZED, detail=exception.detail
+            )
         if token:
             if not token.scheme == "Bearer":
                 raise HTTPException(
diff --git a/tests/routers/test_image.py b/tests/routers/test_image.py
index 501f74a..1ff6d93 100644
--- a/tests/routers/test_image.py
+++ b/tests/routers/test_image.py
@@ -6,9 +6,9 @@
 from PIL import Image
 
 
-def test_export_bitmap_without_jwt_responds_403(client):
+def test_export_bitmap_without_jwt_responds_401(client):
     response = client.post("export_bitmap")
-    assert response.status_code == status.HTTP_403_FORBIDDEN
+    assert response.status_code == status.HTTP_401_UNAUTHORIZED
 
 
 def test_export_bitmap_file_not_found_responds_404(client, authentication_headers):