diff -r 502f6a53519b -r 6dd83e007f56 src/HOL/Library/RBT_Mapping.thy
--- a/src/HOL/Library/RBT_Mapping.thy	Fri Mar 08 13:21:55 2013 +0100
+++ b/src/HOL/Library/RBT_Mapping.thy	Fri Mar 08 13:21:58 2013 +0100
@@ -39,7 +39,7 @@
 
 lemma map_entry_Mapping [code]:
   "Mapping.map_entry k f (Mapping t) = Mapping (map_entry k f t)"
-  apply (transfer fixing: t) by (case_tac "lookup t k") auto
+by (transfer fixing: t, case_tac "lookup t k") auto
 
 lemma keys_Mapping [code]:
   "Mapping.keys (Mapping t) = set (keys t)"