diff --git a/js/ui/windowManager.js b/js/ui/windowManager.js
index 89ccf694e..022cd1eb7 100644
--- a/js/ui/windowManager.js
+++ b/js/ui/windowManager.js
@@ -479,6 +479,10 @@ const WindowManager = new Lang.Class({
                                                 false, -1, 1);
     },
 
+    keepWorkspaceAlive: function(workspace, duration) {
+        this._workspaceTracker.keepWorkspaceAlive(workspace, duration);
+    },
+
     setCustomKeybindingHandler: function(name, modes, handler) {
         if (Meta.keybindings_set_custom_handler(name, handler))
             this.allowKeybinding(name, modes);
diff --git a/js/ui/workspaceThumbnail.js b/js/ui/workspaceThumbnail.js
index 6b631d1d9..c5cd7e360 100644
--- a/js/ui/workspaceThumbnail.js
+++ b/js/ui/workspaceThumbnail.js
@@ -764,8 +764,8 @@ const ThumbnailsBox = new Lang.Class({
                 // to open its first window within some time, as tracked by Shell.WindowTracker.
                 // Here, we only add a very brief timeout to avoid the _immediate_ removal of the
                 // workspace while we wait for the startup sequence to load.
-                Main.keepWorkspaceAlive(global.screen.get_workspace_by_index(newWorkspaceIndex),
-                                        WORKSPACE_KEEP_ALIVE_TIME);
+                Main.wm.keepWorkspaceAlive(global.screen.get_workspace_by_index(newWorkspaceIndex),
+                                           WORKSPACE_KEEP_ALIVE_TIME);
             }
 
             // Start the animation on the workspace (which is actually