--- a/browser/components/sessionstore/RecentlyClosedTabsAndWindowsMenuUtils.jsm
+++ b/browser/components/sessionstore/RecentlyClosedTabsAndWindowsMenuUtils.jsm
@@ -164,17 +164,17 @@ function createEntry(aTagName, aIsWindow
   tabData = aIsWindowsFragment ? aClosedTab
                      : aClosedTab.state;
   let activeIndex = (tabData.index || tabData.entries.length) - 1;
   if (activeIndex >= 0 && tabData.entries[activeIndex]) {
     element.setAttribute("targetURI", tabData.entries[activeIndex].url);
   }
 
   if (!aIsWindowsFragment) {
-    element.addEventListener("click", this._undoCloseMiddleClick, false);
+    element.addEventListener("click", RecentlyClosedTabsAndWindowsMenuUtils._undoCloseMiddleClick, false);
   }
   if (aIndex == 0) {
     element.setAttribute("key", "key_undoClose" + (aIsWindowsFragment? "Window" : "Tab"));
   }
 
   aFragment.appendChild(element);
 }
 
@@ -206,9 +206,9 @@ function createRestoreAllEntry(aDocument
                                   "for (var i = 0; i < " + aEntryCount + "; i++) undoClose" +
                                     (aIsWindowsFragment? "Window" : "Tab") + "();");
   if (aPrefixRestoreAll) {
     aFragment.insertBefore(restoreAllElements, aFragment.firstChild);
   } else {
     aFragment.appendChild(aDocument.createElementNS(kNSXUL, "menuseparator"));
     aFragment.appendChild(restoreAllElements);
   }
-}
+}
\ No newline at end of file