diff -r b75555ec30a4 -r 8ce596cae2a3 src/HOL/BNF/Examples/Derivation_Trees/Prelim.thy
--- a/src/HOL/BNF/Examples/Derivation_Trees/Prelim.thy	Tue Oct 16 17:08:20 2012 +0200
+++ b/src/HOL/BNF/Examples/Derivation_Trees/Prelim.thy	Tue Oct 16 17:33:08 2012 +0200
@@ -8,7 +8,7 @@
 header {* Preliminaries *}
 
 theory Prelim
-imports "../../BNF"
+imports "../../BNF" "../../More_BNFs"
 begin
 
 declare fset_to_fset[simp]