diff --git a/platform/chromium/vapi-background.js b/platform/chromium/vapi-background.js
index 93324e7db..e8114b110 100644
--- a/platform/chromium/vapi-background.js
+++ b/platform/chromium/vapi-background.js
@@ -88,8 +88,8 @@ vAPI.tabs.registerListeners = function() {
     var popupCandidates = Object.create(null);
 
     var PopupCandidate = function(details) {
-        this.targetTabId = details.tabId;
-        this.openerTabId = details.sourceTabId;
+        this.targetTabId = details.tabId.toString();
+        this.openerTabId = details.sourceTabId.toString();
         this.targetURL = details.url;
         this.selfDestructionTimer = null;
     };
diff --git a/src/js/tab.js b/src/js/tab.js
index 7809948bb..5c4745549 100644
--- a/src/js/tab.js
+++ b/src/js/tab.js
@@ -137,7 +137,7 @@ housekeep itself.
     var gcPeriod = 10 * 60 * 1000;
 
     var TabContext = function(tabId) {
-        this.tabId = tabId;
+        this.tabId = tabId.toString();
         this.stack = [];
         this.rawURL =
         this.normalURL =
@@ -414,8 +414,8 @@ vAPI.tabs.onPopup = function(details) {
     //console.debug('vAPI.tabs.onPopup: details = %o', details);
 
     var tabContext = µb.tabContextManager.lookup(details.openerTabId);
-    var openerURL = details.openerURL || '';
-    if ( openerURL === '' && tabContext.tabId === details.openerTabId ) {
+    var openerURL = '';
+    if ( tabContext.tabId === details.openerTabId ) {
         openerURL = tabContext.normalURL;
     }