diff --git a/nibai.rb b/nibai.rb
index a52864f..fc223ef 100755
--- a/nibai.rb
+++ b/nibai.rb
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# coding: utf-8
 require 'cgi'
 
 puts "Content-type: text/html; charset=utf-8\n\n"
@@ -14,7 +15,7 @@
 	<p>2x=#{2*x.to_i}</p>
 	<form action="./nibai.rb" method="POST">
 	  <p><input name="foo">を2倍します.</p>
-	  <p><input type="submit">
+	  <p><input type="submit" value="計算!">
 	  <input type="reset"></p>
 	</form>
 	</body>