diff --git a/ChangeLog b/ChangeLog
index 6791507c7e..3a54f7e546 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Jul 26 18:38:13 2006  Minero Aoki  <aamine@loveruby.net>
+
+	* ext/strscan/strscan.c (strscan_do_scan): always return nil if
+	  p->curr exceeds string size.
+
 Wed Jul 26 18:33:31 2006  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* eval.c (Init_eval): rename #invoke_method and
diff --git a/ext/strscan/strscan.c b/ext/strscan/strscan.c
index dcb70a7747..9529bc3693 100644
--- a/ext/strscan/strscan.c
+++ b/ext/strscan/strscan.c
@@ -1,7 +1,7 @@
 /*
     $Id$
 
-    Copyright (c) 1999-2005 Minero Aoki
+    Copyright (c) 1999-2006 Minero Aoki
 
     This program is free software.
     You can distribute/modify this program under the terms of
@@ -401,6 +401,9 @@ strscan_do_scan(VALUE self, VALUE regex, int succptr, int getstr, int headonly)
     GET_SCANNER(self, p);
 
     CLEAR_MATCH_STATUS(p);
+    if (S_RESTLEN(p) < 0) {
+        return Qnil;
+    }
     if (headonly) {
         ret = onig_match(RREGEXP(regex)->ptr, (UChar* )CURPTR(p),
                          (UChar* )(CURPTR(p) + S_RESTLEN(p)),