diff --git a/core/mui/gtk_extension.rb b/core/mui/gtk_extension.rb
index 8279834..0586247 100644
--- a/core/mui/gtk_extension.rb
+++ b/core/mui/gtk_extension.rb
@@ -192,8 +192,13 @@ class Gtk::Widget < Gtk::Object
 
   # 繧ｦ繧｣繧ｸ繧ｧ繝・ヨ縺ｫ繝・・繝ｫ繝√ャ繝・_text_ 繧偵▽縺代ｋ
   def tooltip(text)
-    Gtk::Tooltips.new.set_tip(self, text, '')
+    tooltip_class.set_tip(self, text, '')
     self end
+
+  private
+  def tooltip_class
+    @tooltip_class ||= Gtk::Tooltips.new
+  end
 end
 
 class Gtk::Container < Gtk::Widget