diff --git a/ChangeLog b/ChangeLog
index f6526f2506..4ea3f8f64d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Oct  1 00:54:32 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* string.c (rb_str_split_m): should use rb_str_subseq() which use
+	  offset and length by bytes.  [ruby-dev:36641]
+
 Wed Oct  1 00:29:48 2008  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* test/ruby/test_settracefunc.rb (test_call, test_class): line number
diff --git a/string.c b/string.c
index 6a6859b1f2..06bb26caa3 100644
--- a/string.c
+++ b/string.c
@@ -5148,7 +5148,7 @@ rb_str_split_m(int argc, VALUE *argv, VALUE str)
 		spat = rb_reg_regcomp(spat);
 		split_type = regexp;
 	    }
-	    else if (rb_enc_mbminlen(enc2) == 1) {
+	    else if (rb_enc_asciicompat(enc2) == 1) {
 		if (RSTRING_LEN(spat) == 1 && RSTRING_PTR(spat)[0] == ' '){
 		    split_type = awk;
 		}
@@ -5224,7 +5224,7 @@ rb_str_split_m(int argc, VALUE *argv, VALUE str)
 		ptr = t;
 		continue;
 	    }
-	    rb_ary_push(result, rb_str_substr(str, ptr - RSTRING_PTR(str), end));
+	    rb_ary_push(result, rb_str_subseq(str, ptr - RSTRING_PTR(str), end));
 	    ptr += end + slen;
 	    if (!NIL_P(limit) && lim <= ++i) break;
 	}