src/HOL/Nat.thy

--- a/src/HOL/Nat.thy	Fri Oct 21 11:17:12 2011 +0200
+++ b/src/HOL/Nat.thy	Fri Oct 21 11:17:14 2011 +0200
@@ -1301,7 +1301,7 @@
 
 end
 
-declare of_nat_code [code, code_unfold, code_inline del]
+declare of_nat_code [code]
 
 text{*Class for unital semirings with characteristic zero.
  Includes non-ordered rings like the complex numbers.*}