src/Pure/Proof/proofchecker.ML

--- a/src/Pure/Proof/proofchecker.ML	Fri Feb 27 16:33:11 2009 +0100
+++ b/src/Pure/Proof/proofchecker.ML	Fri Feb 27 16:38:52 2009 +0100
@@ -56,7 +56,7 @@
       | thm_of _ _ (PAxm (name, _, SOME Ts)) =
           thm_of_atom (Thm.axiom thy name) Ts
 
-      | thm_of _ Hs (PBound i) = List.nth (Hs, i)
+      | thm_of _ Hs (PBound i) = nth Hs i
 
       | thm_of (vs, names) Hs (Abst (s, SOME T, prf)) =
           let