diff --git a/networks-tests.rkt b/networks-tests.rkt
index 10aeb4d..48ec170 100644
--- a/networks-tests.rkt
+++ b/networks-tests.rkt
@@ -76,6 +76,6 @@
                 '((a . (#f #t)) (b . (#f #t))))
 
   (let ([n #hash((a . (not b)) (b . a))]
-        [doms (make-immutable-hash (for/list ([var '(a b)]) (cons var '(#f #t))))])
+        [doms (make-boolean-domains '(a b))])
     (check-equal? (get-interaction-sign n doms 'a 'b) '+)
     (check-equal? (get-interaction-sign n doms 'b 'a) '-)))