diff --git a/custom_components/auth_header/headers.py b/custom_components/auth_header/headers.py
index 764b9b0..bdcaf59 100644
--- a/custom_components/auth_header/headers.py
+++ b/custom_components/auth_header/headers.py
@@ -55,7 +55,7 @@ async def async_login_flow(self, context: Optional[Dict]) -> LoginFlow:
                 [],
                 cast(IPAddress, context.get("conn_ip_address")),
             )
-        remote_user = request.headers[header_name]
+        remote_user = request.headers[header_name].casefold()
         # Translate username to id
         users = await self.store.async_get_users()
         available_users = [