diff --git a/ChangeLog b/ChangeLog
index 4b48b075ab..8db05af59b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Jun  2 20:16:03 2004  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* string.c (str_new4): should share shared instance if it already
+	  exists.  [ruby-dev:23665]
+
 Wed Jun  2 12:41:53 2004  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* io.c (rb_io_gets_m): set lastline ($_) even when read line is
diff --git a/string.c b/string.c
index fcb75821d5..8e7ebff2e9 100644
--- a/string.c
+++ b/string.c
@@ -143,9 +143,9 @@ str_new4(klass, str)
 
     RSTRING(str2)->len = RSTRING(str)->len;
     RSTRING(str2)->ptr = RSTRING(str)->ptr;
-    if (FL_TEST(str, ELTS_SHARED) && !RSTRING(str)->aux.shared) {
-	/* ptr should be null_str */
+    if (FL_TEST(str, ELTS_SHARED)) {
 	FL_SET(str2, ELTS_SHARED);
+	RSTRING(str2)->aux.shared = RSTRING(str)->aux.shared;
     }
     else {
 	FL_SET(str, ELTS_SHARED);
@@ -165,7 +165,6 @@ rb_str_new4(orig)
     klass = rb_obj_class(orig);
     if (FL_TEST(orig, ELTS_SHARED) && (str = RSTRING(orig)->aux.shared) && klass == RBASIC(str)->klass) {
 	long ofs;
-	str = RSTRING(orig)->aux.shared;
 	ofs = RSTRING(str)->len - RSTRING(orig)->len;
 	if (ofs > 0) {
 	    str = str_new3(klass, str);