diff --git a/src/calibre/gui2/layout.py b/src/calibre/gui2/layout.py
index 3332d25e00..54afd6ca60 100644
--- a/src/calibre/gui2/layout.py
+++ b/src/calibre/gui2/layout.py
@@ -229,6 +229,7 @@ class SearchBar(QFrame):  # {{{
 
         parent.advanced_search_toggle_action = ac = parent.search.add_action('gear.png', QLineEdit.LeadingPosition)
         parent.addAction(ac)
+        ac.setToolTip(_('Advanced search'))
         parent.keyboard.register_shortcut('advanced search toggle',
                 _('Advanced search'), default_keys=("Shift+Ctrl+F",),
                 action=ac)