diff --git a/ChangeLog b/ChangeLog
index 61494b675c..b14a0e1abc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,9 @@ Tue Apr  8 10:34:10 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
 	* load.c (rb_require_safe): should check fname path after $SAFE is
 	  properly set.  [ruby-dev:34268]
 
+	* re.c (rb_reg_quote): should always copy the quoting string.
+	  [ruby-core:16235]
+
 Tue Apr  8 10:30:29 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* common.mk (prelude.c): depends on enc/prelude.rb.
diff --git a/re.c b/re.c
index 3f115cd04b..f0776a1fe8 100644
--- a/re.c
+++ b/re.c
@@ -2759,11 +2759,11 @@ rb_reg_quote(VALUE str)
 	}
         s += clen;
     }
+    tmp = rb_str_new3(str);
     if (ascii_only) {
-        str = rb_str_new3(str);
-        rb_enc_associate(str, rb_usascii_encoding());
+        rb_enc_associate(tmp, rb_usascii_encoding());
     }
-    return str;
+    return tmp;
 
   meta_found:
     tmp = rb_str_new(0, RSTRING_LEN(str)*2);