diff --git a/lib/assert.js b/lib/assert.js
index 8d9e0e3cf..c9b9ca14d 100644
--- a/lib/assert.js
+++ b/lib/assert.js
@@ -158,11 +158,16 @@ assert.deepEqual = function deepEqual(actual, expected, message) {
 
 function _deepEqual(actual, expected) {
   // 7.1. All identical values are equivalent, as determined by ===.
-  if (actual === expected) {
+  if (actual === expected)
     return true;
+
+  // Convert to primitives, if supported
+  actual = actual.valueOf ? actual.valueOf() : actual;
+  expected = expected.valueOf ? expected.valueOf() : expected;
+
   // 7.2. If the expected value is a Date object, the actual value is
   // equivalent if it is also a Date object that refers to the same time.
-  } else if (actual instanceof Date && expected instanceof Date) {
+  if (actual instanceof Date && expected instanceof Date) {
     return actual.getTime() === expected.getTime();
 
   // 7.3. Other pairs that do not both pass typeof value == "object",
@@ -192,6 +197,7 @@ function isArguments (object) {
 function objEquiv (a, b) {
   if (isUndefinedOrNull(a) || isUndefinedOrNull(b))
     return false;
+
   // an identical "prototype" property.
   if (a.prototype !== b.prototype) return false;
   //~~~I've managed to break Object.keys through screwy arguments passing.
diff --git a/test/test-base.js b/test/test-base.js
index 64b8c8bbd..d1c0d35a8 100644
--- a/test/test-base.js
+++ b/test/test-base.js
@@ -115,7 +115,8 @@ exports.testSame = makeTest('same',
 exports.testEqual = makeTest('equal', [1, 1], [1, 2]);
 exports.testNotEqual = makeTest('notEqual', [1, 2], [1, 1]);
 exports.testDeepEqual = makeTest('deepEqual',
-    [{one: 1}, {one: 1}], [{one: 1}, {two: 2}]
+  [{one: 1, two: 2}, {one: 1, two: {valueOf:function() {return 2;}}}],
+  [{one: 1, two: 2}, {two: 2}]
 );
 exports.testNotDeepEqual = makeTest('notDeepEqual',
     [{one: 1}, {two: 2}], [{one: 1}, {one: 1}]