diff --git a/lib/attribute.js b/lib/attribute.js
index 98a7c68..0588dcc 100644
--- a/lib/attribute.js
+++ b/lib/attribute.js
@@ -737,6 +737,9 @@ validators.dependencies = function validateDependencies (instance, schema, optio
  * @return {ValidatorResult|null}
  */
 validators['enum'] = function validateEnum (instance, schema, options, ctx) {
+  if(!schema['enum']) {
+    return null;
+  }
   if (!(schema['enum'] instanceof Array)) {
     throw new SchemaError("enum expects an array", schema);
   }
diff --git a/test/attributes.js b/test/attributes.js
index b29154b..fac7edb 100644
--- a/test/attributes.js
+++ b/test/attributes.js
@@ -294,6 +294,11 @@ describe('Attributes', function () {
     it('should validate if a required field has a value out of enum', function () {
       return this.validator.validate({'the_field':'bar'}, {'type': 'object', 'properties':{'the_field': {'enum': ['foo', 'bar', 'baz'], 'required': true}}}).valid.should.be.true;
     });
+    
+    it('should validate if number enum is undefined', function () {
+      return this.validator.validate(1, {'type': 'number', 'enum': undefined}).valid.should.be.true;
+    });
+    
   });
 
   describe('description', function () {