--- a/browser/components/customizableui/content/panelUI.js
+++ b/browser/components/customizableui/content/panelUI.js
@@ -415,22 +415,21 @@ const PanelUI = {
     }
     items.appendChild(fragment);
   },
 
   _updateQuitTooltip: function() {
 #ifndef XP_WIN
 #ifdef XP_MACOSX
     let tooltipId = "quit-button.tooltiptext.mac";
+#else
+    let tooltipId = "quit-button.tooltiptext.linux2";
+#endif
     let brands = Services.strings.createBundle("chrome://branding/locale/brand.properties");
     let stringArgs = [brands.GetStringFromName("brandShortName")];
-#else
-    let tooltipId = "quit-button.tooltiptext.linux";
-    let stringArgs = [];
-#endif
 
     let key = document.getElementById("key_quitApplication");
     stringArgs.push(ShortcutUtils.prettifyShortcut(key));
     let tooltipString = CustomizableUI.getLocalizedProperty({x: tooltipId}, "x", stringArgs);
     let quitButton = document.getElementById("PanelUI-quit");
     quitButton.setAttribute("tooltiptext", tooltipString);
 #endif
   },

--- a/browser/locales/en-US/chrome/browser/customizableui/customizableWidgets.properties
+++ b/browser/locales/en-US/chrome/browser/customizableui/customizableWidgets.properties
@@ -86,13 +86,14 @@ feed-button.tooltiptext = Subscribe to this page…
 characterencoding-button.label = Character Encoding
 characterencoding-button.tooltiptext2 = Show Character Encoding options
 
 email-link-button.label = Email Link
 # LOCALIZATION NOTE (email-link-button.tooltiptext2): Use the unicode ellipsis char,
 # \u2026, or use "..." if \u2026 doesn't suit traditions in your locale.
 email-link-button.tooltiptext2 = Email Link…
 
-# LOCALIZATION NOTE(quit-button.tooltiptext.linux): %S is the keyboard shortcut
-quit-button.tooltiptext.linux = Quit (%S)
+# LOCALIZATION NOTE(quit-button.tooltiptext.linux2): %1$S is the brand name (e.g. Firefox),
+# %2$S is the keyboard shortcut
+quit-button.tooltiptext.linux2 = Quit %1$S (%2$S)
 # LOCALIZATION NOTE(quit-button.tooltiptext.mac): %1$S is the brand name (e.g. Firefox),
 # %2$S is the keyboard shortcut
 quit-button.tooltiptext.mac = Quit %1$S (%2$S)