diff -r 1d80798e8d8a -r b27bbb021df1 src/HOL/Library/Dlist.thy
--- a/src/HOL/Library/Dlist.thy	Fri Oct 12 15:08:29 2012 +0200
+++ b/src/HOL/Library/Dlist.thy	Fri Oct 12 18:58:20 2012 +0200
@@ -8,7 +8,7 @@
 
 subsection {* The type of distinct lists *}
 
-typedef (open) 'a dlist = "{xs::'a list. distinct xs}"
+typedef 'a dlist = "{xs::'a list. distinct xs}"
   morphisms list_of_dlist Abs_dlist
 proof
   show "[] \<in> {xs. distinct xs}" by simp