diff --git a/platform/safari/vapi-background.js b/platform/safari/vapi-background.js
index 953535882..eb7af74e1 100644
--- a/platform/safari/vapi-background.js
+++ b/platform/safari/vapi-background.js
@@ -240,7 +240,7 @@
     /******************************************************************************/
 
     vAPI.isNoTabId = function(tabId) {
-        return tabId.toString() === '-1';
+        return tabId.toString() === this.noTabId;
     };
 
     vAPI.noTabId = '-1';