diff --git a/ChangeLog b/ChangeLog
index 0fad107c80..4c15fda4a3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+Tue Apr  2 17:38:20 2013  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* re.c (rb_reg_to_s): suppress duplicated charclass warning.
+	  Regexp#to_s suppress extra its whole regexp options by calling
+	  onig_new with its source, but it doesn't call rb_reg_preprocess.
+	  Therefore its Unicode escapes (\u{XXXX}) are given as is,
+	  and it may cause duplicated charclass warning for example
+	  "[\u{33}]" (3 is duplicated) or "[\u{a}\u{b}]" (u is duplicated).
+	  [ruby-core:53649] [Bug #8151]
+
 Tue Apr  2 16:00:06 2013  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* vm_dump.c (rb_print_backtrace): separate to ease showing C backtrace.
diff --git a/re.c b/re.c
index 91d34eb0cd..16d7e3450c 100644
--- a/re.c
+++ b/re.c
@@ -571,12 +571,15 @@ rb_reg_to_s(VALUE re)
 	}
 	if (*ptr == ':' && ptr[len-1] == ')') {
 	    Regexp *rp;
+	    VALUE verbose = ruby_verbose;
+	    ruby_verbose = Qfalse;
 
 	    ++ptr;
 	    len -= 2;
             err = onig_new(&rp, ptr, ptr + len, ONIG_OPTION_DEFAULT,
 			   enc, OnigDefaultSyntax, NULL);
 	    onig_free(rp);
+	    ruby_verbose = verbose;
 	}
 	if (err) {
 	    options = RREGEXP(re)->ptr->options;
diff --git a/test/ruby/test_regexp.rb b/test/ruby/test_regexp.rb
index e17cd6f962..3fa0fcf83c 100644
--- a/test/ruby/test_regexp.rb
+++ b/test/ruby/test_regexp.rb
@@ -915,6 +915,9 @@ class TestRegexp < Test::Unit::TestCase
 
     bug7471 = '[ruby-core:50344]'
     assert_warning('', bug7471) { Regexp.new('[\D]') =~ "\u3042" }
+
+    bug8151 = '[ruby-core:53649]'
+    assert_warning(/\A\z/, bug8151) { Regexp.new('(?:[\u{33}])').to_s }
   end
 
   def test_property_warn