--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -918,16 +918,17 @@ var gBrowserInit = {
 
     // setup simple gestures support
     gGestureSupport.init(true);
 
     // setup history swipe animation
     gHistorySwipeAnimation.init();
 
     if (window.opener && !window.opener.closed &&
+        window.opener.document.documentURIObject.schemeIs("chrome") &&
         PrivateBrowsingUtils.isWindowPrivate(window) == PrivateBrowsingUtils.isWindowPrivate(window.opener)) {
       let openerSidebarBox = window.opener.document.getElementById("sidebar-box");
       // If the opener had a sidebar, open the same sidebar in our window.
       // The opener can be the hidden window too, if we're coming from the state
       // where no windows are open, and the hidden window has no sidebar box.
       if (openerSidebarBox && !openerSidebarBox.hidden) {
         let sidebarCmd = openerSidebarBox.getAttribute("sidebarcommand");
         let sidebarCmdElem = document.getElementById(sidebarCmd);