diff --git a/index.js b/index.js
index 639b1bd..301996c 100644
--- a/index.js
+++ b/index.js
@@ -8,18 +8,21 @@
  * @api public
  */
 
-exports.set = function (obj, path, val) {
+exports.set = function(obj, path, val) {
   var segs = path.split('.');
   var attr = segs.pop();
   var src = obj;
 
   for (var i = 0; i < segs.length; i++) {
     var seg = segs[i];
+    if (!isSafe(obj, seg)) return src;
     obj[seg] = obj[seg] || {};
     obj = obj[seg];
   }
 
-  obj[attr] = val;
+  if (isSafe(obj, attr)) {
+    obj[attr] = val;
+  }
 
   return src;
 };
@@ -33,7 +36,7 @@ exports.set = function (obj, path, val) {
  * @api public
  */
 
-exports.get = function (obj, path) {
+exports.get = function(obj, path) {
   var segs = path.split('.');
   var attr = segs.pop();
 
@@ -55,19 +58,42 @@ exports.get = function (obj, path) {
  * @api public
  */
 
-exports.delete = function (obj, path) {
+exports.delete = function(obj, path) {
   var segs = path.split('.');
   var attr = segs.pop();
 
   for (var i = 0; i < segs.length; i++) {
     var seg = segs[i];
     if (!obj[seg]) return;
+    if (!isSafe(obj, seg)) return;
     obj = obj[seg];
   }
 
+  if (!isSafe(obj, attr)) return;
+
   if (Array.isArray(obj)) {
-    obj.splice(path, 1);
+    obj.splice(attr, 1);
   } else {
     delete obj[attr];
   }
 };
+
+function isSafe(obj, prop) {
+  if (isObject(obj)) {
+    return obj[prop] === undefined || hasOwnProperty(obj, prop);
+  }
+
+  if (Array.isArray(obj)) {
+    return !isNaN(parseInt(prop, 10));
+  }
+
+  return false;
+}
+
+function hasOwnProperty(obj, prop) {
+  return Object.prototype.hasOwnProperty.call(obj, prop);
+}
+
+function isObject(obj) {
+  return Object.prototype.toString.call(obj) === '[object Object]';
+}
diff --git a/package.json b/package.json
index 5821ec0..2ea87e2 100644
--- a/package.json
+++ b/package.json
@@ -3,7 +3,7 @@
   "publishConfig": {
     "access": "public"
   },
-  "version": "1.0.2",
+  "version": "1.0.3",
   "description": "Get and set object properties with dot notation",
   "main": "index.js",
   "scripts": {
diff --git a/test/index.js b/test/index.js
index 1f5e4f5..f11b7ba 100644
--- a/test/index.js
+++ b/test/index.js
@@ -1,15 +1,15 @@
 var assert = require('assert');
 var dot = require('..');
 
-var tests = module.exports = {
-  'test set': function () {
+var tests = (module.exports = {
+  'test set': function() {
     var obj = {};
     var ret = dot.set(obj, 'cool.aid', 'rocks');
     assert(obj.cool.aid === 'rocks');
     assert(obj === ret);
   },
 
-  'test get': function () {
+  'test get': function() {
     var obj = {};
     obj.cool = {};
     obj.cool.aid = 'rocks';
@@ -17,17 +17,44 @@ var tests = module.exports = {
     assert(value === 'rocks');
   },
 
-  'test delete': function () {
+  'test delete': function() {
     var obj = {};
     obj.cool = {};
     obj.cool.aid = 'rocks';
     obj.cool.hello = ['world'];
     dot.delete(obj, 'cool.aid');
     dot.delete(obj, 'cool.hello.0');
-    assert(!obj.cool.hasOwnProperty('aid'))
+    assert(!obj.cool.hasOwnProperty('aid'));
     assert(obj.cool.hello.length == 0);
+  },
+
+  'test prototype pollution': function() {
+    var obj = {};
+    obj.cool = {};
+    obj.cool.aid = 'rocks';
+    obj.cool.hello = ['world'];
+    dot.set(obj, '__proto__', 'test');
+    dot.set(obj, '__proto__.toString', 'test');
+    dot.set(obj, 'toString', 'test');
+    dot.set(obj, 'cool.hello.__proto__', 'test');
+    dot.set(obj, 'cool.hello.__proto__.toString', 'test');
+    dot.set(obj, 'cool.hello.toString', 'test');
+    assert(obj.__proto__ === {}.__proto__);
+    assert(obj.toString === Object.prototype.toString);
+    assert(obj.cool.hello.__proto__ === [].__proto__);
+    assert(obj.cool.hello.toString === Array.prototype.toString);
+    dot.delete(obj, '__proto__.toString', 'test');
+    dot.delete(obj, '__proto__', 'test');
+    dot.delete(obj, 'toString', 'test');
+    dot.delete(obj, 'cool.hello.__proto__.toString', 'test');
+    dot.delete(obj, 'cool.hello.__proto__', 'test');
+    dot.delete(obj, 'cool.hello.toString', 'test');
+    assert(obj.__proto__ === {}.__proto__);
+    assert(obj.toString === Object.prototype.toString);
+    assert(obj.cool.hello.__proto__ === [].__proto__);
+    assert(obj.cool.hello.toString === Array.prototype.toString);
   }
-}
+});
 
 for (var t in tests) {
   tests[t]();