diff --git a/ChangeLog b/ChangeLog
index b912141ba4..486e09ddbc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Nov 15 15:29:39 2001  Nobuyoshi Nakada  <nobu.nakada@nifty.ne.jp>
+
+	* array.c (rb_ary_join): non-nil separator must be converted to
+	  String.  and separators' total length was wrong.
+
 Thu Nov 15 03:37:17 2001  Usaku Nakamura  <usa@ruby-lang.org>
 
 	* hash.c (ruby_setenv): remove USE_WIN32_RTL_ENV block since it's
diff --git a/array.c b/array.c
index 0dfa3aef40..f77cfc7401 100644
--- a/array.c
+++ b/array.c
@@ -804,8 +804,9 @@ rb_ary_join(ary, sep)
 	    len += 10;
 	}
     }
-    if (!NIL_P(sep) && TYPE(sep) == T_STRING) {
-	len += RSTRING(sep)->len * RARRAY(ary)->len - 1;
+    if (!NIL_P(sep)) {
+	StringValue(sep);
+	len += RSTRING(sep)->len * (RARRAY(ary)->len - 1);
     }
     result = rb_str_buf_new(len);
     for (i=0; i<RARRAY(ary)->len; i++) {