diff --git a/ChangeLog b/ChangeLog
index 8ac0b35812..ca07a9b9ab 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,7 @@
-Mon Jul 15 02:21:29 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Mon Jul 15 02:21:33 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* encoding.c (enc_inspect): use PRIsVALUE to preserve the result
+	  encoding.
 
 	* encoding.c (enc_set_index): deal with terminator so that
 	  rb_enc_set_index also works.
diff --git a/encoding.c b/encoding.c
index 244ef05f5e..e1b14dcda5 100644
--- a/encoding.c
+++ b/encoding.c
@@ -1023,11 +1023,10 @@ rb_enc_tolower(int c, rb_encoding *enc)
 static VALUE
 enc_inspect(VALUE self)
 {
-    VALUE str = rb_sprintf("#<%s:%s%s>", rb_obj_classname(self),
-		      rb_enc_name((rb_encoding*)DATA_PTR(self)),
-		      (enc_dummy_p(self) ? " (dummy)" : ""));
-    ENCODING_CODERANGE_SET(str, ENCINDEX_US_ASCII, ENC_CODERANGE_7BIT);
-    return str;
+    return rb_enc_sprintf(rb_usascii_encoding(),
+			  "#<%"PRIsVALUE":%s%s>", rb_obj_class(self),
+			  rb_enc_name((rb_encoding*)DATA_PTR(self)),
+			  (enc_dummy_p(self) ? " (dummy)" : ""));
 }
 
 /*