diff --git a/collections-lib/data/collection/indexable.rkt b/collections-lib/data/collection/indexable.rkt
index 9c17b50..40150e2 100644
--- a/collections-lib/data/collection/indexable.rkt
+++ b/collections-lib/data/collection/indexable.rkt
@@ -7,15 +7,25 @@
 
 (provide
  gen:indexable indexable? indexable/c
- ref set-ref)
+ ref set-ref update-ref)
 
 (define-generics indexable
   (ref indexable . _)
   (set-ref indexable . _)
+  (update-ref indexable . _)
   #:defaults
   ([hash? (define ref hash-ref)
-          (define set-ref hash-set)]
+          (define set-ref hash-set)
+          (define update-ref hash-update)]
    [dict? (define ref dict-ref)
-          (define set-ref dict-set)]
+          (define set-ref dict-set)
+          (define update-ref dict-update)]
    [sequence? (define ref nth)
-              (define set-ref set-nth)]))
+              (define set-ref set-nth)
+              (define update-ref update-nth)])
+  #:fallbacks
+  [(define/generic -ref ref)
+   (define/generic -set-ref set-ref)
+   (define (update-ref indexable index proc)
+     (let ([old (-ref indexable index)])
+       (-set-ref indexable index (proc old))))])
diff --git a/collections-test/tests/data/collection/indexable.rkt b/collections-test/tests/data/collection/indexable.rkt
new file mode 100644
index 0000000..8034033
--- /dev/null
+++ b/collections-test/tests/data/collection/indexable.rkt
@@ -0,0 +1,61 @@
+#lang racket/base
+
+(require rackunit
+         data/collection
+         racket/stream
+         racket/generic
+         racket/function) 
+
+(struct my-list (items)
+  #:transparent
+  #:methods gen:indexable
+  [(define/generic -ref ref)
+   (define/generic -set-ref set-ref)
+   (define (ref indexable . args)
+     (define pos (car args))
+     (list-ref (my-list-items indexable)
+               pos))
+   (define (set-ref indexable . args)
+     (define pos (car args))
+     (define item (cadr args))
+     (define ls (my-list-items indexable))
+     (my-list (-set-ref ls pos item)))])
+
+(test-case "ref"
+  "list"
+  (check-equal? (ref '(a b) 1) 'b)
+  "vector"
+  (check-equal? (ref #(a b c) 1) 'b)
+  "hash"
+  (check-equal? (ref (hash 'a 'b) 'a) 'b)
+  "alist"
+  (check-equal? (ref '((a . b)) 'a) 'b)
+  "custom data type my-list"
+  (check-equal? (ref (my-list '(a b)) 1) 'b))
+
+(test-case "set-ref"
+  "list"
+  (check-equal? (set-ref '(a b) 0 'c)
+                '(c b))
+  "hash"
+  (check-equal? (set-ref (hash 'a 'b) 'a 'c)
+                (hash 'a 'c))
+  "alist"
+  (check-equal? (set-ref '((a . b)) 'a 'c)
+                '((a . c)))
+  "custom data type my-list"
+  (check-equal? (set-ref (my-list '(a b)) 0 'c)
+                (my-list '(c b))))
+
+(test-case "update-ref"
+  "list"
+  (check-equal? (update-ref '(a b) 0 identity)
+                '(a b))
+  "hash"
+  (check-equal? (update-ref (hash 'a 'b) 'a identity)
+                (hash 'a (identity 'b)))
+  "alist"
+  (check-equal? (update-ref '((a . b)) 'a identity)
+                `((a . ,(identity 'b))))
+  (check-equal? (update-ref (my-list '(a b)) 1 identity)
+                (my-list `(a ,(identity 'b)))))