diff --git a/docs/modules/Zipper.ts.md b/docs/modules/Zipper.ts.md
index b7d9ba8..ff23faf 100644
--- a/docs/modules/Zipper.ts.md
+++ b/docs/modules/Zipper.ts.md
@@ -418,7 +418,7 @@ Creates a new zipper.
 **Signature**
 
 ```ts
-export declare const make: <A>(lefts: A[], focus: A, rights: A[]) => Zipper<A>
+export declare const make: <A>(lefts: readonly A[], focus: A, rights: readonly A[]) => Zipper<A>
 ```
 
 Added in v0.1.6
diff --git a/src/Zipper.ts b/src/Zipper.ts
index 2ee29a7..98f1ac0 100644
--- a/src/Zipper.ts
+++ b/src/Zipper.ts
@@ -58,10 +58,14 @@ export interface Zipper<A> {
  * @category constructors
  * @since 0.1.6
  */
-export const make: <A>(lefts: Array<A>, focus: A, rights: Array<A>) => Zipper<A> = (lefts, focus, rights) => ({
+export const make: <A>(lefts: ReadonlyArray<A>, focus: A, rights: ReadonlyArray<A>) => Zipper<A> = (
   lefts,
   focus,
   rights
+) => ({
+  lefts: lefts.slice(),
+  focus,
+  rights: rights.slice()
 })
 
 /**