diff --git a/module/language/objcode/spec.scm b/module/language/objcode/spec.scm
index a4cb0621d..bbd745412 100644
--- a/module/language/objcode/spec.scm
+++ b/module/language/objcode/spec.scm
@@ -53,11 +53,6 @@
             (lp (acons (binding:index b) (list b) ret)
                 (cdr locs))))))))
 
-(define (program-free-variables program)
-  (list->vector
-   (map (lambda (i) (program-free-variable-ref program i))
-        (iota (program-num-free-variables program)))))
-
 (define (decompile-value x env opts)
   (cond
    ((program? x)
diff --git a/module/system/vm/program.scm b/module/system/vm/program.scm
index f3892cbb3..30f8c7ecd 100644
--- a/module/system/vm/program.scm
+++ b/module/system/vm/program.scm
@@ -20,7 +20,8 @@
 
 (define-module (system vm program)
   #:use-module (system base pmatch)
-  #:use-module (ice-9 optargs)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-26)
   #:export (make-program
 
             make-binding binding:name binding:boxed? binding:index
@@ -35,10 +36,11 @@
             arity:nreq arity:nopt arity:rest? arity:kw arity:allow-other-keys?
 
             program-arguments-alist program-lambda-list
-            
+
             program-meta
             program-objcode program? program-objects
             program-module program-base
+            program-free-variables
             program-num-free-variables
             program-free-variable-ref program-free-variable-set!))
 
@@ -190,6 +192,14 @@
       ,@(if (pair? key) (cons #:key key) '())
       . ,rest)))
 
+(define (program-free-variables prog)
+  "Return the list of free variables of PROG."
+  (let ((count (program-num-free-variables prog)))
+    (unfold (lambda (i) (>= i count))
+            (cut program-free-variable-ref prog <>)
+            1+
+            0)))
+
 (define (write-program prog port)
   (format port "#<procedure ~a~a>"
           (or (procedure-name prog)