--- a/browser/base/content/browser-sidebar.js
+++ b/browser/base/content/browser-sidebar.js
@@ -74,17 +74,17 @@ var SidebarUI = {
   },
 
   /**
    * Opens the switcher panel if it's closed, or closes it if it's open.
    */
   toggleSwitcherPanel() {
     if (this._switcherPanel.state == "open" || this._switcherPanel.state == "showing") {
       this.hideSwitcherPanel();
-    } else {
+    } else if (this._switcherPanel.state == "closed") {
       this.showSwitcherPanel();
     }
   },
 
   hideSwitcherPanel() {
     this._switcherPanel.hidePopup();
   },