diff --git a/examples/nqueens/NQueens.gf b/examples/nqueens/NQueens.gf
index bd236bf55..960bef6d1 100644
--- a/examples/nqueens/NQueens.gf
+++ b/examples/nqueens/NQueens.gf
@@ -1,10 +1,13 @@
 abstract NQueens = Nat ** {
 
+cat S ;
 cat Matrix Nat ;
 cat [Nat] ;
 cat Vec (s,l : Nat) [Nat] ;
 cat Sat Nat Nat [Nat] ;
 
+data queens : Matrix (succ (succ (succ (succ (succ (succ (succ (succ zero)))))))) -> S ;
+
 data nilV  : ({s} : Nat) -> ({c} : [Nat]) -> Vec s zero c ;
      consV : ({l},j,k : Nat) -> 
                 let s = succ (plus j k)
diff --git a/examples/nqueens/NQueensAscii.gf b/examples/nqueens/NQueensAscii.gf
index 261d28f7a..a5bb2ed76 100644
--- a/examples/nqueens/NQueensAscii.gf
+++ b/examples/nqueens/NQueensAscii.gf
@@ -1,8 +1,10 @@
 concrete NQueensAscii of NQueens = NatAscii ** {
 
-lincat Matrix, Vec = Str ;
+lincat S, Matrix, Vec = Str ;
        ListNat, Sat = {} ;
 
+lin queens m = m ;
+
 lin nilV _ _ = "" ;
     consV _ j k _ _ v = j ++ "X" ++ k ++ ";" ++ v ;