diff --git a/ChangeLog b/ChangeLog
index 95313ae649..36b813d7e7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -6,6 +6,12 @@ Thu Oct 30 14:45:45 2008  Martin Duerst  <duerst@it.aoyama.ac.jp>
 	* enc/trans/iso-8859-1-tbl.rb: new file to avoid having to
 	  treat ISO-8859-1 as special
 
+Thu Oct 30 14:10:46 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* pack.c (pack_pack): templates a, A, Z should propagate encoding
+	  of original strings.  templates b, B, h, H brings ASCII-8BIT to
+	  the result.
+
 Thu Oct 30 10:34:20 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* ruby.c (moreswitches): splits option string and passes arguments.
diff --git a/pack.c b/pack.c
index df25231610..2ecb2d68d6 100644
--- a/pack.c
+++ b/pack.c
@@ -519,8 +519,15 @@ pack_pack(VALUE ary, VALUE fmt)
 		ptr = RSTRING_PTR(from);
 		plen = RSTRING_LEN(from);
 		OBJ_INFECT(res, from);
-		enc = rb_enc_compatible(res, from);
-		rb_enc_associate(res, enc);
+		switch (type) {
+		  case 'a': case 'A': case 'Z':
+		    enc = rb_enc_compatible(res, from);
+		    rb_enc_associate(res, enc);
+		    break;
+		  default:
+		    rb_enc_associate(res, rb_ascii8bit_encoding());
+		    break;
+		}
 	    }
 
 	    if (p[-1] == '*')