--- a/browser/base/content/browser-places.js
+++ b/browser/base/content/browser-places.js
@@ -1414,24 +1414,31 @@ var BookmarkingUI = {
 
     let onBookmarksMenuHidden = event => {
       if (event.target == event.currentTarget) {
         updatePlacesContextMenu(true);
 
         Services.prefs.removeObserver(this.RECENTLY_BOOKMARKED_PREF, prefObserver, false);
         PlacesUtils.bookmarks.removeObserver(this._recentlyBookmarkedObserver);
         this._recentlyBookmarkedObserver = null;
-        placesContextMenu.removeEventListener("popupshowing", onPlacesContextMenuShowing);
+        if (placesContextMenu) {
+          placesContextMenu.removeEventListener("popupshowing", onPlacesContextMenuShowing);
+        }
         bookmarksMenu.removeEventListener("popuphidden", onBookmarksMenuHidden);
       }
     };
 
     Services.prefs.addObserver(this.RECENTLY_BOOKMARKED_PREF, prefObserver, false);
     PlacesUtils.bookmarks.addObserver(this._recentlyBookmarkedObserver, true);
-    placesContextMenu.addEventListener("popupshowing", onPlacesContextMenuShowing);
+
+    // The context menu doesn't exist in non-browser windows on Mac
+    if (placesContextMenu) {
+      placesContextMenu.addEventListener("popupshowing", onPlacesContextMenuShowing);
+    }
+
     bookmarksMenu.addEventListener("popuphidden", onBookmarksMenuHidden);
   },
 
   _populateRecentBookmarks(aHeaderItem, aExtraCSSClass = "") {
     while (aHeaderItem.nextSibling &&
            aHeaderItem.nextSibling.localName == "menuitem") {
       aHeaderItem.nextSibling.remove();
     }