diff --git a/ChangeLog b/ChangeLog
index bf21d8d178..babc64953b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Nov  8 21:57:59 2012  Masaki Matsushita  <glass.saga@gmail.com>
+
+	* re.c (rb_memsearch): performance improvement by using memchr().
+	  [ruby-dev:45397] [Feature #6173]
+
 Thu Nov  8 19:02:50 2012  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* lib/net/protocol.rb (Net::InternetMessageIO#each_crlf_line):
diff --git a/re.c b/re.c
index 70e3c3fe34..ea11f1c015 100644
--- a/re.c
+++ b/re.c
@@ -220,12 +220,12 @@ rb_memsearch(const void *x0, long m, const void *y0, long n, rb_encoding *enc)
 	return 0;
     }
     else if (m == 1) {
-	const unsigned char *ys = y, *ye = ys + n;
-	for (; y < ye; ++y) {
-	    if (*x == *y)
-		return y - ys;
-	}
-	return -1;
+	const unsigned char *ys;
+
+	if (ys = memchr(y, *x, n))
+	    return ys - y;
+	else
+	    return -1;
     }
     else if (m <= SIZEOF_VALUE) {
 	return rb_memsearch_ss(x0, m, y0, n);