diff --git a/js/ui/altTab.js b/js/ui/altTab.js
index da4c99641..a1a5f1612 100644
--- a/js/ui/altTab.js
+++ b/js/ui/altTab.js
@@ -724,7 +724,19 @@ ThumbnailList.prototype = {
     _init : function(windows) {
         SwitcherList.prototype._init.call(this);
 
+        let activeWorkspace = global.screen.get_active_workspace();
+
+        // We fake the value of "separatorAdded" when the app has no window
+        // on the current workspace, to avoid displaying a useless separator in
+        // that case.
+        let separatorAdded = windows.length == 0 || windows[0].get_workspace() != activeWorkspace;
+
         for (let i = 0; i < windows.length; i++) {
+            if (!separatorAdded && windows[i].get_workspace() != activeWorkspace) {
+              this.addSeparator();
+              separatorAdded = true;
+            }
+
             let mutterWindow = windows[i].get_compositor_private();
             let windowTexture = mutterWindow.get_texture ();
             let [width, height] = windowTexture.get_size();