diff -r 6e1f3d609a68 -r 403585a89772 src/Pure/Isar/isar_cmd.ML
--- a/src/Pure/Isar/isar_cmd.ML	Sat May 08 16:53:53 2010 +0200
+++ b/src/Pure/Isar/isar_cmd.ML	Sat May 08 19:14:13 2010 +0200
@@ -313,7 +313,7 @@
 
 (* pretty_setmargin *)
 
-fun pretty_setmargin n = Toplevel.imperative (fn () => Pretty.setmargin n);
+fun pretty_setmargin n = Toplevel.imperative (fn () => Pretty.margin_default := n);
 
 
 (* print parts of theory and proof context *)