diff --git a/lib/crypto.js b/lib/crypto.js
index 7efa6243f98..a787e09c348 100644
--- a/lib/crypto.js
+++ b/lib/crypto.js
@@ -458,6 +458,19 @@ DiffieHellman.prototype.setPrivateKey = function(key, encoding) {
 
 
 exports.pbkdf2 = function(password, salt, iterations, keylen, callback) {
+  if (typeof callback !== 'function')
+    throw new Error('No callback provided to pbkdf2');
+
+  return pbkdf2(password, salt, iterations, keylen, callback);
+};
+
+
+exports.pbkdf2Sync = function(password, salt, iterations, keylen) {
+  return pbkdf2(password, salt, iterations, keylen);
+};
+
+
+function pbkdf2(password, salt, iterations, keylen, callback) {
   password = toBuf(password);
   salt = toBuf(salt);
 
@@ -476,11 +489,8 @@ exports.pbkdf2 = function(password, salt, iterations, keylen, callback) {
     var ret = binding.PBKDF2(password, salt, iterations, keylen);
     return ret.toString(encoding);
   }
-};
+}
 
-exports.pbkdf2Sync = function(password, salt, iterations, keylen) {
-  return exports.pbkdf2(password, salt, iterations, keylen);
-};
 
 
 exports.randomBytes = randomBytes;
diff --git a/test/simple/test-crypto-binary-default.js b/test/simple/test-crypto-binary-default.js
index 535a578a3bf..85c5447a2b1 100644
--- a/test/simple/test-crypto-binary-default.js
+++ b/test/simple/test-crypto-binary-default.js
@@ -657,7 +657,7 @@ assert.strictEqual(rsaVerify.verify(rsaPubPem, rsaSignature, 'hex'), true);
 // Test PBKDF2 with RFC 6070 test vectors (except #4)
 //
 function testPBKDF2(password, salt, iterations, keylen, expected) {
-  var actual = crypto.pbkdf2(password, salt, iterations, keylen);
+  var actual = crypto.pbkdf2Sync(password, salt, iterations, keylen);
   assert.equal(actual, expected);
 
   crypto.pbkdf2(password, salt, iterations, keylen, function(err, actual) {