diff --git a/knots/parallelism.scm b/knots/parallelism.scm
index c98ca3f..f15dbe8 100644
--- a/knots/parallelism.scm
+++ b/knots/parallelism.scm
@@ -22,6 +22,7 @@
   #:use-module (srfi srfi-71)
   #:use-module (srfi srfi-9)
   #:use-module (srfi srfi-9 gnu)
+  #:use-module (srfi srfi-43)
   #:use-module (ice-9 match)
   #:use-module (ice-9 control)
   #:use-module (ice-9 exceptions)
@@ -57,7 +58,7 @@
            (lambda (exn)
              (put-message
               reply
-              (list 'exception exn)))
+              (cons 'exception exn)))
          (lambda ()
            (with-exception-handler
                (lambda (exn)
@@ -78,7 +79,7 @@
                    (lambda ()
                      (start-stack #t (thunk)))
                  (lambda vals
-                   (put-message reply vals))))))
+                   (put-message reply (cons 'result vals)))))))
          #:unwind? #t))
      #:parallel? #t)
     reply))
@@ -88,10 +89,10 @@
                         reply-channels)))
     (map
      (match-lambda
-       (('exception exn)
+       (('exception . exn)
         (raise-exception exn))
-       (result
-        (apply values result)))
+       (('result . vals)
+        (apply values vals)))
      responses)))
 
 (define (fibers-batch-map proc parallelism-limit . lists)
@@ -114,9 +115,18 @@
              (channel-indexes '()))
     (if (and (eq? #f next-to-process-index)
              (null? channel-indexes))
-        (if (vector? (first lists))
-            result-vec
-            (vector->list result-vec))
+        (let ((processed-result-vec
+               (vector-map
+                (lambda (_ result-or-exn)
+                  (match result-or-exn
+                    (('exception . exn)
+                     (raise-exception exn))
+                    (('result . vals)
+                     (car vals))))
+                result-vec)))
+          (if (vector? (first lists))
+              processed-result-vec
+              (vector->list processed-result-vec)))
 
         (if (or (= (length channel-indexes)
                    (min parallelism-limit vecs-length))
@@ -132,18 +142,13 @@
                          (get-operation
                           (vector-ref result-vec index))
                          (lambda (result)
-                           (match result
-                             (('exception exn)
-                              (raise-exception exn))
-                             (_
-                              (vector-set! result-vec
-                                           index
-                                           (first result))
-
-                              (values next-to-process-index
-                                      (lset-difference =
-                                                       channel-indexes
-                                                       (list index))))))))
+                           (vector-set! result-vec
+                                        index
+                                        result)
+                           (values next-to-process-index
+                                   (lset-difference =
+                                                    channel-indexes
+                                                    (list index))))))
                       channel-indexes)))))
               (loop new-index
                     new-channel-indexes))
@@ -217,10 +222,10 @@
       (if (null? active-channels)
           (map
            (match-lambda
-             ((#f . ('exception exn))
+             ((#f . ('exception . exn))
               (raise-exception exn))
-             ((#f . ('result val))
-              val))
+             ((#f . ('result . vals))
+              (car vals)))
            channels-to-results)
           (loop
            (perform-operation
@@ -237,12 +242,7 @@
                           (map (match-lambda
                                  ((c . r)
                                   (if (eq? channel c)
-                                      (cons #f
-                                            (match result
-                                              (('exception exn)
-                                               result)
-                                              (_
-                                               (list 'result result))))
+                                      (cons #f result)
                                       (cons c r))))
                                channels-to-results)))
                        #f))))
@@ -263,7 +263,7 @@
              reply-channel
              (with-exception-handler
                  (lambda (exn)
-                   (list 'exception exn))
+                   (cons 'exception exn))
                (lambda ()
                  (with-exception-handler
                      (lambda (exn)
@@ -294,7 +294,7 @@
       (put-message input-channel (cons reply-channel args))
       (match (get-message reply-channel)
         (('result . vals) (apply values vals))
-        (('exception exn)
+        (('exception . exn)
          (raise-exception exn))))))
 
 (define-record-type <parallelism-limiter>