diff --git a/src/js/heuristicblocking.js b/src/js/heuristicblocking.js
index 7209c166b9..f6b3416dcd 100644
--- a/src/js/heuristicblocking.js
+++ b/src/js/heuristicblocking.js
@@ -124,11 +124,9 @@ HeuristicBlocker.prototype = {
     let tab_origin = self.tabOrigins[details.tabId];
 
     // return early if tab origin is a localhost address
-    ['127.0', 'localhost', 'http://localhost'].forEach((localhost) => {
-      if (tab_origin.startsWith(localhost)) {
-        return {};
-      }
-    });
+    if (window.isPrivateDomain(tab_origin)) {
+      return {};
+    }
 
     // ignore first-party requests
     if (!tab_origin || !utils.isThirdPartyDomain(request_origin, tab_origin)) {