diff --git a/lib/srfi/231/transforms.scm b/lib/srfi/231/transforms.scm
index 853262ad..ab6c4776 100644
--- a/lib/srfi/231/transforms.scm
+++ b/lib/srfi/231/transforms.scm
@@ -392,7 +392,10 @@
   (assert (and (procedure? operator)
                (array? array)
                (every array? arrays)
-               (every (lambda (a) (interval= (array-domain array) a)) arrays)))
+               (every (lambda (a)
+                        (interval= (array-domain array)
+                                   (array-domain a)))
+                      arrays)))
   (if (null? arrays)
       (interval-fold-left (array-getter array)
                           (lambda (accumulator array-element)
@@ -409,7 +412,10 @@
   (assert (and (procedure? operator)
                (array? array)
                (every array? arrays)
-               (every (lambda (a) (interval= (array-domain array) a)) arrays)))
+               (every (lambda (a)
+                        (interval= (array-domain array)
+                                   (array-domain a)))
+                      arrays)))
   (if (null? arrays)
       (interval-fold-right (array-getter array)
                            (lambda (array-element accumulator)