diff --git a/ChangeLog b/ChangeLog
index 5801955a65..0b2d36bf09 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Thu Dec 20 09:06:54 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* string.c (rb_str_index): wrong starting position.
+
 Thu Dec 20 06:34:27 2007  Koichi Sasada  <ko1@atdot.net>
 
 	* compile.c (iseq_compile_each): add pop after throw as return.
diff --git a/string.c b/string.c
index 5e6e0ae626..f1910af782 100644
--- a/string.c
+++ b/string.c
@@ -1457,6 +1457,7 @@ rb_str_index(VALUE str, VALUE sub, long offset)
     s = RSTRING_PTR(str);
     if (offset) {
 	offset = str_offset(s, RSTRING_END(str), offset, enc, IS_7BIT(str));
+	s += offset;
     }
     if (slen == 0) return offset;
     /* need proceed one character at a time */