--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -4947,16 +4947,27 @@ nsDocShell::DisplayLoadError(nsresult aE
       } else {
         error.AssignLiteral("nssFailure2");
       }
     }
   } else if (NS_ERROR_PHISHING_URI == aError ||
              NS_ERROR_MALWARE_URI == aError ||
              NS_ERROR_UNWANTED_URI == aError ||
              NS_ERROR_FORBIDDEN_URI == aError) {
+    // This ensures we never display the error page in a frame:
+    nsCOMPtr<nsIDocShellTreeItem> parent;
+    GetSameTypeParent(getter_AddRefs(parent));
+    if (parent) {
+      nsCOMPtr<nsIDocShellTreeItem> sameTypeRoot;
+      parent->GetSameTypeRootTreeItem(getter_AddRefs(sameTypeRoot));
+      nsCOMPtr<nsIDocShell> rootShell = do_QueryInterface(sameTypeRoot);
+      return rootShell->DisplayLoadError(aError, aURI, aURL, aFailedChannel,
+          aDisplayedErrorPage);
+    }
+
     nsAutoCString host;
     aURI->GetHost(host);
     CopyUTF8toUTF16(host, formatStrs[0]);
     formatStrCount = 1;
 
     // Malware and phishing detectors may want to use an alternate error
     // page, but if the pref's not set, we'll fall back on the standard page
     nsAdoptingCString alternateErrorPage =