diff --git a/ChangeLog b/ChangeLog
index 674caee0a7..00c5c35763 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Mon Sep 29 00:30:20 2008  Takeyuki Fujioka  <xibbar@ruby-lang.org>
+
+	* lib/cgi/html.rb (CGI::HtmlExtension::{radio_group, checkbox_group}):
+	can specify the false as checked or selected value.
+	[ruby-core:18306], [ruby-core:18307]
+
+	* test/cgi/test_cgi_tag_helper.rb: add a test.
+
 Sun Sep 28 23:08:38 2008  Takeyuki Fujioka  <xibbar@ruby-lang.org>
 
 	* lib/cgi/html.rb (CGI::HtmlExtension::popup_menu):
diff --git a/lib/cgi/html.rb b/lib/cgi/html.rb
index aac53f9256..74aa730be7 100644
--- a/lib/cgi/html.rb
+++ b/lib/cgi/html.rb
@@ -248,12 +248,12 @@ class CGI
         if value.kind_of?(String)
           checkbox(name, value) + value
         else
-          if value[value.size - 1] == true
-            checkbox(name, value[0], true) +
-            value[value.size - 2]
+          if value[-1] == true || value[-1] == false
+            checkbox(name, value[0],  value[-1]) +
+            value[-2]
           else
             checkbox(name, value[0]) +
-            value[value.size - 1]
+            value[-1]
           end
         end
       }.join
@@ -703,12 +703,12 @@ class CGI
         if value.kind_of?(String)
           radio_button(name, value) + value
         else
-          if value[value.size - 1] == true
-            radio_button(name, value[0], true) +
-            value[value.size - 2]
+          if value[-1] == true || value[-1] == false
+            radio_button(name, value[0],  value[-1]) +
+            value[-2]
           else
             radio_button(name, value[0]) +
-            value[value.size - 1]
+            value[-1]
           end
         end
       }.join
diff --git a/test/cgi/test_cgi_tag_helper.rb b/test/cgi/test_cgi_tag_helper.rb
index 38533a11e8..618130b822 100755
--- a/test/cgi/test_cgi_tag_helper.rb
+++ b/test/cgi/test_cgi_tag_helper.rb
@@ -313,6 +313,17 @@ class CGITagHelperTest < Test::Unit::TestCase
     assert_match(/^<INPUT .*VALUE="aa".*>bb<INPUT .*VALUE="cc".*>dd$/,str)
     assert_match(/^<INPUT .*TYPE="radio".*>bb<INPUT .*TYPE="radio".*>dd$/,str)
     assert_match(/^<INPUT .*NAME="foo".*>bb<INPUT .*NAME="foo".*>dd$/,str)
+    str=cgi.checkbox_group("foo",["aa","bb"],["cc","dd",true])
+    assert_match(/^<INPUT .*VALUE="aa".*>bb<INPUT .*VALUE="cc".*>dd$/,str)
+    assert_match(/^<INPUT .*TYPE="checkbox".*>bb<INPUT .*TYPE="checkbox".*>dd$/,str)
+    assert_match(/^<INPUT .*NAME="foo".*>bb<INPUT .*NAME="foo".*>dd$/,str)
+    assert_match(/^<INPUT .*>bb<INPUT .*CHECKED.*>dd$/,str)
+    if RUBY_VERSION>="1.9"
+      str=cgi.radio_group("foo",["aa","bb"],["cc","dd",false])
+      assert_match(/^<INPUT .*VALUE="aa".*>bb<INPUT .*VALUE="cc".*>dd$/,str)
+      assert_match(/^<INPUT .*TYPE="radio".*>bb<INPUT .*TYPE="radio".*>dd$/,str)
+      assert_match(/^<INPUT .*NAME="foo".*>bb<INPUT .*NAME="foo".*>dd$/,str)
+    end
   end
   
 =begin