diff --git a/knots/parallelism.scm b/knots/parallelism.scm
index fc3d039..1210c19 100644
--- a/knots/parallelism.scm
+++ b/knots/parallelism.scm
@@ -238,45 +238,47 @@
                        #f))))
               channels-to-results))))))))
 
-(define* (fiberize proc #:key (parallelism 1))
-  (let ((channel (make-channel)))
-    (for-each
-     (lambda _
-       (spawn-fiber
-        (lambda ()
-          (while #t
-            (let ((reply-channel args (car+cdr
-                                       (get-message channel))))
-              (put-message
-               reply-channel
-               (call-with-escape-continuation
-                (lambda (return)
-                  (with-exception-handler
-                      (lambda (exn)
-                        (match (fluid-ref %stacks)
-                          ((stack-tag . prompt-tag)
-                           (let ((stack (make-stack #t
-                                                    0 prompt-tag
-                                                    0 (and prompt-tag 1))))
-                             (return (list 'exception exn stack))))))
-                    (lambda ()
-                      (call-with-values
-                          (lambda ()
-                            (start-stack #t (apply proc args)))
-                        (lambda vals
-                          (cons 'result vals)))))))))))
-        #:parallel? #t))
-     (iota parallelism))
+(define* (fiberize proc
+                   #:key (parallelism 1)
+                   (input-channel (make-channel))
+                   (process-channel input-channel))
+  (for-each
+   (lambda _
+     (spawn-fiber
+      (lambda ()
+        (while #t
+          (let ((reply-channel args (car+cdr
+                                     (get-message process-channel))))
+            (put-message
+             reply-channel
+             (call-with-escape-continuation
+              (lambda (return)
+                (with-exception-handler
+                    (lambda (exn)
+                      (match (fluid-ref %stacks)
+                        ((stack-tag . prompt-tag)
+                         (let ((stack (make-stack #t
+                                                  0 prompt-tag
+                                                  0 (and prompt-tag 1))))
+                           (return (list 'exception exn stack))))))
+                  (lambda ()
+                    (call-with-values
+                        (lambda ()
+                          (start-stack #t (apply proc args)))
+                      (lambda vals
+                        (cons 'result vals)))))))))))
+      #:parallel? #t))
+   (iota parallelism))
 
-    (lambda args
-      (let ((reply-channel (make-channel)))
-        (put-message channel (cons reply-channel args))
-        (match (get-message reply-channel)
-          (('result . vals) (apply values vals))
-          (('exception exn stack)
-           (let ((knots-exn
-                  (make-knots-exception stack)))
-             (raise-exception
-              (make-exception
-               knots-exn
-               exn)))))))))
+  (lambda args
+    (let ((reply-channel (make-channel)))
+      (put-message input-channel (cons reply-channel args))
+      (match (get-message reply-channel)
+        (('result . vals) (apply values vals))
+        (('exception exn stack)
+         (let ((knots-exn
+                (make-knots-exception stack)))
+           (raise-exception
+            (make-exception
+             knots-exn
+             exn))))))))