diff -r dc6be28d7f4e -r c69542757a4d src/HOL/Library/Nested_Environment.thy
--- a/src/HOL/Library/Nested_Environment.thy	Mon Aug 16 14:21:54 2004 +0200
+++ b/src/HOL/Library/Nested_Environment.thy	Mon Aug 16 14:22:27 2004 +0200
@@ -5,7 +5,9 @@
 
 header {* Nested environments *}
 
-theory Nested_Environment = Main:
+theory Nested_Environment
+import Main
+begin
 
 text {*
   Consider a partial function @{term [source] "e :: 'a => 'b option"};