diff --git a/ChangeLog b/ChangeLog
index 68dce9e092..227f9d20cd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,11 @@ Thu Mar 14 08:57:41 2002  Nobuyoshi Nakada  <nobu.nakada@nifty.ne.jp>
 
 	* dir.c (rb_push_glob): avoid SEGV when a block given.
 
+Thu Mar 14 00:16:02 2002  Nobuyoshi Nakada  <nobu.nakada@nifty.ne.jp>
+
+	* string.c (rb_str_subpat_set): must make str independent after
+	  rb_reg_search() matched.
+
 Wed Mar 13 19:05:15 2002  Akinori MUSHA  <knu@iDaemons.org>
 
 	* dir.c: FNM_PERIOD is obsoleted and FNM_DOTMATCH is introduced
diff --git a/string.c b/string.c
index d83913c0ee..41d697bce0 100644
--- a/string.c
+++ b/string.c
@@ -1252,6 +1252,7 @@ rb_str_subpat_set(str, re, nth, val)
     }
     end = RMATCH(match)->END(nth);
     len = end - start;
+    rb_str_modify(str);
     rb_str_update(str, start, len, val);
 }