diff --git a/ext/tk/lib/tk.rb b/ext/tk/lib/tk.rb
index d22f7b43d7..a2c4a7d61f 100644
--- a/ext/tk/lib/tk.rb
+++ b/ext/tk/lib/tk.rb
@@ -3911,7 +3911,7 @@ class TkRoot<TkWindow
     Tk_WINDOWS["."] = new
   end
 =end
-  def TkRoot.new(keys=nil)
+  def TkRoot.new(keys=nil, &b)
     unless TkCore::INTERP.tk_windows['.']
       TkCore::INTERP.tk_windows['.'] = 
 	super(:without_creating=>true, :widgetname=>'.')
@@ -3926,7 +3926,8 @@ class TkRoot<TkWindow
 	end
       }
     end
-    return root
+    root.instance_eval(&b) if block_given?
+    root
   end
 
   WidgetClassName = 'Tk'.freeze