diff -r acfdd493f5c4 -r 5de27a5fc5ed src/HOL/Tools/specification_package.ML
--- a/src/HOL/Tools/specification_package.ML	Thu Apr 21 18:56:03 2005 +0200
+++ b/src/HOL/Tools/specification_package.ML	Thu Apr 21 18:57:18 2005 +0200
@@ -110,7 +110,7 @@
 	fun unthaw (f as (a,S)) =
 	    (case assoc (fmap',a) of
 		 NONE => TVar f
-	       | SOME b => TFree (b,S))
+	       | SOME (b, _) => TFree (b,S))
     in
 	map_term_types (map_type_tvar unthaw) t
     end