diff --git a/Core_DOM/preliminaries/Hiding_Type_Variables.thy b/Core_DOM/preliminaries/Hiding_Type_Variables.thy
index 3c593ef..e31e560 100644
--- a/Core_DOM/preliminaries/Hiding_Type_Variables.thy
+++ b/Core_DOM/preliminaries/Hiding_Type_Variables.thy
@@ -276,9 +276,8 @@ structure Hide_Tvar : HIDE_TVAR = struct
         val thy = Proof_Context.theory_of ctx
 
         fun parse_ast ((Ast.Constant const)::[]) = (const,NONE)
-          | parse_ast ((Ast.Constant sort)::(Ast.Constant const)::[]) 
-                                      = (const,SOME sort)  
-          |  parse_ast _ = error("AST type not supported.") 
+          | parse_ast (sort::(Ast.Constant const)::[]) = (const,SOME sort)
+          | parse_ast _ = error("AST type not supported.")
 
         val (decorated_name, decorated_sort) = parse_ast ast 
 
@@ -295,9 +294,9 @@ structure Hide_Tvar : HIDE_TVAR = struct
             let fun mk_tvar n = 
                case decorated_sort of 
                   NONE      => Ast.Variable(name_of_tvar n)
-                | SOME sort =>  Ast.Appl([Ast.Constant("_ofsort"),
+                | SOME sort => Ast.Appl([Ast.Constant("_ofsort"),
                                                Ast.Variable(name_of_tvar n),
-                                                   Ast.Constant(sort)])
+                                                   sort])
             in
               map mk_tvar (#tvars default_info)
             end