diff --git a/lib/mocha.js b/lib/mocha.js
index 21a3269528..667300e36e 100644
--- a/lib/mocha.js
+++ b/lib/mocha.js
@@ -345,11 +345,12 @@ Mocha.prototype.randomize = function randomize(seed) {
 
 /**
  * Generate a random seed.
- * @returns {number} Unsigned 32-bit integer
+ * @returns {string} Hexadecimal string
  */
 Mocha.seed = function seed() {
-  return Random.integer(0, utils.MAX_SAFE_INTEGER)(Random.engines.mt19937()
-    .autoSeed());
+  var engine = Random.engines.mt19937()
+    .autoSeed();
+  return utils.toHex(Random.integer(0, utils.MAX_SAFE_INTEGER)(engine));
 };
 
 /**
diff --git a/lib/utils.js b/lib/utils.js
index f406dd5b0c..edb03a35ad 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -816,6 +816,15 @@ exports.isPromise = function isPromise(value) {
   return typeof value === 'object' && typeof value.then === 'function';
 };
 
+/**
+ * Given integer `int`, try to convert it to a hex string.
+ * @param {number} int Integer
+ * @returns {string} Hexadecimal representation thereof
+ */
+exports.toHex = function toHex(int) {
+  return '0x' + int.toString(16).toUpperCase();
+};
+
 /**
  * Returns `true` if `value` is a "safe" 32-bit unsigned int.
  * @param {*} [value] Value to test
diff --git a/test/acceptance/random.js b/test/acceptance/random.js
index bde963bc3c..4d22f76731 100644
--- a/test/acceptance/random.js
+++ b/test/acceptance/random.js
@@ -3,20 +3,18 @@
 var mocha = require('../..');
 // yuk
 var Mocha = mocha.Mocha || mocha;
+var utils = require('../../lib/utils');
 
 describe('random option', function() {
   describe('seed', function() {
-    it('should return a number', function() {
+    it('should return a hex string', function() {
       expect(Mocha.seed())
         .to
-        .be
-        .a('number');
+        .match(/^0x[0-9A-F]+/);
     });
 
-    it('should return a positive number', function() {
-      expect(Mocha.seed() > 0)
-        .to
-        .be(true);
+    it('should be a valid seed', function() {
+      expect(utils.toSafeUnsignedInteger(Mocha.seed())).to.be.a('number');
     });
 
     it('should return a finite number', function() {
diff --git a/test/utils.spec.js b/test/utils.spec.js
index 6459b4a778..d37fab0714 100644
--- a/test/utils.spec.js
+++ b/test/utils.spec.js
@@ -228,6 +228,12 @@ describe('utils', function() {
     });
   });
 
+  describe('.toHex', function() {
+    it('should convert an integer to hex', function() {
+      utils.toHex(0xDEADBEEF).should.equal('0xDEADBEEF');
+    });
+  });
+
   describe('.isPromise', function() {
     it('should return true if the value is Promise-ish', function() {
       utils.isPromise({then: function() {}}).should.be.true;