diff --git a/functions.rkt b/functions.rkt
index 8fad63b..8739b75 100644
--- a/functions.rkt
+++ b/functions.rkt
@@ -216,7 +216,7 @@
   (module+ test
     (test-case "tabulate/pv/01"
       (check-equal? (tabulate/pv/01 2 (pvλ (x y)
-                                           (cast (modulo (+ x y) 2) (U Zero One))))
+                                           (assert-type (modulo (+ x y) 2) (U Zero One))))
                     '((0 0 0) (0 1 1) (1 0 1) (1 1 0)))))
 
   (: tabulate*/pv/01 (-> Positive-Integer (Listof (-> (U Zero One) * (U Zero One)))
@@ -226,8 +226,8 @@
 
   (module+ test
     (test-case "tabulate*/pv/01"
-      (check-equal? (tabulate*/pv/01 2 `(,(pvλ (x y) (cast (min x y) (U Zero One)))
-                                         ,(pvλ (x y) (cast (max x y) (U Zero One)))))
+      (check-equal? (tabulate*/pv/01 2 `(,(pvλ (x y) (assert-type (min x y) (U Zero One)))
+                                         ,(pvλ (x y) (assert-type (max x y) (U Zero One)))))
                     '((0 0 0 0) (0 1 0 1) (1 0 0 1) (1 1 1 1)))))
 
   (: tabulate/list/boolean (-> Positive-Integer (-> (Listof Boolean) Boolean)
@@ -261,7 +261,7 @@
     (test-case "tabulate/list/01"
       (check-equal?
        (tabulate/list/01 2 (λ (xs)
-                             (cast (modulo (+ (car xs) (cadr xs)) 2) (U Zero One))))
+                             (assert-type (modulo (+ (car xs) (cadr xs)) 2) (U Zero One))))
        '((0 0 0) (0 1 1) (1 0 1) (1 1 0)))))
 
   (: tabulate*/list/01 (-> Positive-Integer (Listof (-> (Listof (U Zero One)) (U Zero One)))
@@ -273,8 +273,8 @@
     (test-case "tabulate*/list/01"
       (check-equal? (tabulate*/list/01
                      2
-                     `(,(λ (xs) (cast (min (car xs) (cadr xs)) (U Zero One)))
-                       ,(λ (xs) (cast (max (car xs) (cadr xs)) (U Zero One)))))
+                     `(,(λ (xs) (assert-type (min (car xs) (cadr xs)) (U Zero One)))
+                       ,(λ (xs) (assert-type (max (car xs) (cadr xs)) (U Zero One)))))
                     '((0 0 0 0) (0 1 0 1) (1 0 0 1) (1 1 1 1)))))
 
   (: table->function/list (All (a) (-> (Listof (Listof a))
@@ -324,7 +324,7 @@
   (: enumerate-boolean-tables (-> Positive-Integer (Sequenceof (Listof (Listof Boolean)))))
   (define (enumerate-boolean-tables n)
     (define inputs (boolean-power n))
-    (define outputs (boolean-power/stream (cast (expt 2 n) Integer)))
+    (define outputs (boolean-power/stream (assert-type (expt 2 n) Integer)))
 
     (: append-outputs (-> (Listof (Listof Boolean)) (Listof Boolean)
                           (Listof (Listof Boolean))))
@@ -395,7 +395,7 @@
   (: random-boolean-table (-> Positive-Integer (Listof (Listof Boolean))))
   (define (random-boolean-table n)
     (define ins (boolean-power n))
-    (define outs (stream-take (in-random 2) (cast (expt 2 n) Nonnegative-Integer)))
+    (define outs (stream-take (in-random 2) (assert-type (expt 2 n) Nonnegative-Integer)))
     (for/list ([i ins] [o outs])
       (append i (list (if (= o 1) #t #f)))))
 
@@ -492,9 +492,9 @@
 
   (: read-org-tbfs (->* (String) (#:headers Boolean) (Listof tbf)))
   (define (read-org-tbfs str #:headers [headers #f])
-    (define sexp (cast (read-org-sexp str) (Listof Any)))
+    (define sexp (assert-type (read-org-sexp str) (Listof Any)))
     (define sexp-clean (cond [headers (cdr sexp)] [else sexp]))
-    (lists->tbfs (cast sexp-clean (Listof (Listof Real)))))
+    (lists->tbfs (assert-type sexp-clean (Listof (Listof Real)))))
 
   (module+ test
     (test-case "read-org-tbfs"