diff --git a/README.md b/README.md
index 3035f249a..ca828e557 100644
--- a/README.md
+++ b/README.md
@@ -24,7 +24,7 @@ json separate from validating it, via the `cast` method.
     - [`ValidationError(String|Array<String> errors, Any value, String path)`](#validationerrorstringarraystring-errors-any-value-string-path)
   - [mixed](#mixed)
     - [`mixed.clone()`](#mixedclone)
-    - [`mixed.label(String label)`](#mixedlabel)
+    - [`mixed.label(String label)`](#mixedlabelstring-label)
     - [`mixed.concat(Schema schema)`](#mixedconcatschema-schema)
     - [`mixed.validate(Any value, [Object options, Function callback])`](#mixedvalidateany-value-object-options-function-callback)
     - [`mixed.isValid(Any value, [Object options, Function callback]) -> Promise`](#mixedisvalidany-value-object-options-function-callback---promise)
diff --git a/lib/mixed.js b/lib/mixed.js
index 20c068663..870049efb 100644
--- a/lib/mixed.js
+++ b/lib/mixed.js
@@ -239,8 +239,6 @@ SchemaType.prototype = {
 
     if (typeof opts.message !== 'string' || typeof opts.test !== 'function') throw new TypeError('`message` and `test` are required parameters');
 
-    if (next._whitelist.length) throw new Error('Cannot add tests when specific valid values are specified');
-
     var validate = createValidation(opts);
 
     var isExclusive = opts.exclusive || opts.name && next._exclusive[opts.name] === true;
diff --git a/src/mixed.js b/src/mixed.js
index d994b9303..0085920bb 100644
--- a/src/mixed.js
+++ b/src/mixed.js
@@ -250,9 +250,6 @@ SchemaType.prototype = {
     if (typeof opts.message !== 'string' || typeof opts.test !== 'function')
       throw new TypeError('`message` and `test` are required parameters')
 
-    if (next._whitelist.length)
-      throw new Error('Cannot add tests when specific valid values are specified')
-
     var validate = createValidation(opts);
 
     var isExclusive = (
diff --git a/test/mixed.js b/test/mixed.js
index 660046d81..fd09001da 100644
--- a/test/mixed.js
+++ b/test/mixed.js
@@ -76,6 +76,11 @@ describe( 'Mixed Types ', function(){
         .oneOf(['hello'])
         .isValid(undefined)
         .should.eventually.equal(true),
+      mixed()
+        .oneOf(['hello'])
+        .required()
+        .isValid(null)
+        .should.eventually.equal(false),
       string()
         .nullable()
         .oneOf(['hello'])
@@ -96,7 +101,10 @@ describe( 'Mixed Types ', function(){
       inst.validate(5).should.be.rejected.then(function(err){
         err.errors[0].should.equal('this must not be one the following values: 5, hello')
       }),
-      inst.oneOf([5]).isValid(5).should.eventually.equal(true)
+      inst.oneOf([5]).isValid(5).should.eventually.equal(true),
+
+      inst.isValid(null).should.eventually.equal(true),
+      inst.required().isValid(null).should.eventually.equal(false)
     ])
   })