diff --git a/zerver/lib/subdomains.py b/zerver/lib/subdomains.py
index 88df7ef31f..4adc120388 100644
--- a/zerver/lib/subdomains.py
+++ b/zerver/lib/subdomains.py
@@ -23,9 +23,7 @@ def get_subdomain(request):
 
 def is_subdomain_root_or_alias(request):
     # type: (HttpRequest) -> bool
-    subdomain = _extract_subdomain(request)
-    return (subdomain == Realm.SUBDOMAIN_FOR_ROOT_DOMAIN
-            or subdomain in settings.ROOT_SUBDOMAIN_ALIASES)
+    return get_subdomain(request) == Realm.SUBDOMAIN_FOR_ROOT_DOMAIN
 
 def user_matches_subdomain(realm_subdomain, user_profile):
     # type: (Optional[Text], UserProfile) -> bool