diff --git a/brain/validator/dataset.py b/brain/validator/dataset.py
index c845157c5..efb3b64f3 100644
--- a/brain/validator/dataset.py
+++ b/brain/validator/dataset.py
@@ -8,6 +8,7 @@
 
 from voluptuous import Schema, Required, All, Any, Length
 from voluptuous.humanize import validate_with_humanized_errors
+from six import string_types
 
 
 class Validator(object):
@@ -38,9 +39,9 @@ def validate_classification(self, data):
 
         current_errors = []
         schema = Schema({
-            Required('dependent-variable'): All(unicode, Length(min=1)),
+            Required('dependent-variable'): All(string_types, Length(min=1)),
             Required('independent-variables'): [{
-                Required(All(unicode, Length(min=1))): Any(int, float),
+                Required(All(string_types, Length(min=1))): Any(int, float),
             }],
         })
 
@@ -69,7 +70,7 @@ def validate_regression(self, data):
         schema = Schema({
             Required('dependent-variable'): Any(int, float),
             Required('independent-variables'): [{
-                Required(All(unicode, Length(min=1))): Any(int, float),
+                Required(All(string_types, Length(min=1))): Any(int, float),
             }],
         })