diff -r 7cc639e20cb2 -r 79c1d2bbe5a9 src/Pure/Isar/args.ML
--- a/src/Pure/Isar/args.ML	Thu Apr 29 16:53:08 2010 +0200
+++ b/src/Pure/Isar/args.ML	Thu Apr 29 16:55:22 2010 +0200
@@ -205,7 +205,7 @@
   >> (fn Type (c, _) => c | TFree (a, _) => a | _ => "");
 
 fun const strict =
-  Scan.peek (fn ctxt => named_term (ProofContext.read_const (Context.proof_of ctxt) strict))
+  Scan.peek (fn ctxt => named_term (ProofContext.read_const (Context.proof_of ctxt) strict dummyT))
   >> (fn Const (c, _) => c | Free (x, _) => x | _ => "");
 
 fun const_proper strict =