diff --git a/ChangeLog b/ChangeLog
index e18f0af513..04ef3ebb63 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri Jul 22 21:18:20 2011  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* lib/uri/generic.rb (WFKV_): unroll the loop of regexp.
+
+	* lib/uri/generic.rb (URI.decode_www_form_component): ditto.
+
 Fri Nov 22 12:43:52 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* util.c (ruby_strtod): ignore too long fraction part, which does not
diff --git a/lib/uri/common.rb b/lib/uri/common.rb
index 264fa053ed..b9335ebd04 100644
--- a/lib/uri/common.rb
+++ b/lib/uri/common.rb
@@ -762,7 +762,7 @@ module URI
   #
   # See URI.encode_www_form_component, URI.decode_www_form
   def self.decode_www_form_component(str, enc=Encoding::UTF_8)
-    raise ArgumentError, "invalid %-encoding (#{str})" unless /\A(?:%\h\h|[^%]+)*\z/ =~ str
+    raise ArgumentError, "invalid %-encoding (#{str})" unless /\A[^%]*(?:%\h\h[^%]*)*\z/ =~ str
     str.gsub(/\+|%\h\h/, TBLDECWWWCOMP_).force_encoding(enc)
   end
 
@@ -798,7 +798,7 @@ module URI
     str
   end
 
-  WFKV_ = '(?:%\h\h|[^%#=;&])' # :nodoc:
+  WFKV_ = '(?:[^%#=;&]*(?:%\h\h[^%#=;&]*)*)' # :nodoc:
 
   # Decode URL-encoded form data from given +str+.
   #