diff --git a/sudoku.lispbm b/sudoku.lispbm
index f2a337a..33eb997 100644
--- a/sudoku.lispbm
+++ b/sudoku.lispbm
@@ -4,10 +4,12 @@
     (lambda (x)
       (foldr
        (lambda (y z)
-         (match (filter (lambda (q) (= q y)) nums)
-           (((? r) . nil) (match (filter (lambda (q) (= r q)) x)
-                                 (((? _)) z)
-                                 (_ nil)))
-           (_ nil)))
+         (match y
+            (nil z)
+            (_ (match (filter (lambda (q) (= q y)) nums)
+                (((? r) . nil) (match (filter (lambda (q) (eq r q)) x)
+                                (((? _)) z)
+                                (_ nil)))
+                (_ nil)))))
        t
        x)))