diff --git a/ChangeLog b/ChangeLog
index 23d5855288..b18d68d37d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,7 +1,10 @@
-Thu Feb  7 18:57:04 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Thu Feb  7 19:11:39 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* string.c (rb_str_dup): reverted unneeded change.  [ruby-dev:33634]
 
+	* string.c (rb_str_replace): makes frozen shared string before
+	  sharing.
+
 Thu Feb  7 16:33:51 2008  Tanaka Akira  <akr@fsij.org>
 
 	* io.c (io_reopen): don't change access mode for stdin, stdout and
diff --git a/string.c b/string.c
index a9e90f2848..e24ca623dc 100644
--- a/string.c
+++ b/string.c
@@ -3049,7 +3049,7 @@ rb_str_replace(VALUE str, VALUE str2)
     }
     else {
 	rb_str_modify(str);
-	str_replace_shared(str, str2);
+	str_replace_shared(str, rb_str_new4(str2));
     }
 
     OBJ_INFECT(str, str2);