diff --git a/package.json b/package.json
index f014b7b..90ba843 100644
--- a/package.json
+++ b/package.json
@@ -16,7 +16,9 @@
     "test": "istanbul cover _mocha test.js --report html -- -R spec",
     "prepublish": "npm run test"
   },
-  "dependencies": {},
+  "dependencies": {
+    "seamless-immutable": "^7.1.2"
+  },
   "devDependencies": {
     "chai": "^3.5.0",
     "coveralls": "^2.11.14",
diff --git a/test.js b/test.js
index e6ab631..2c8105f 100644
--- a/test.js
+++ b/test.js
@@ -4,6 +4,7 @@
 
 var expect = require('chai').expect
 var op = require('./index.js')
+const Immutable = require('seamless-immutable')
 
 describe('set', function () {
   it('should set a deep key without modifying the original object', function () {
@@ -95,6 +96,37 @@ describe('set', function () {
 
     expect(newObj.a.b).to.be.equal(2)
   })
+
+  it('should should replace contents of an array inside an object', function () {
+    var obj = {
+      foo: {
+        bar: [
+          {
+            baz: 'fou',
+            biz: 'bar'
+          }, {
+            baz: 'foo',
+            biz: 'bar'
+          }
+        ]
+      }
+    }
+    var immutableObj = Immutable(obj)
+    var newObj = op.set(immutableObj, 'foo.bar.0.baz', 'foo')
+    expect(newObj).to.be.equal(Immutable({
+      foo: {
+        bar: [
+          {
+            baz: 'foo',
+            biz: 'bar'
+          }, {
+            baz: 'foo',
+            biz: 'bar'
+          }
+        ]
+      }
+    }))
+  })
 })
 
 describe('insert', function () {