diff --git a/postgres_stats/aggregates.py b/postgres_stats/aggregates.py
index 4e59a00..f83bcfd 100644
--- a/postgres_stats/aggregates.py
+++ b/postgres_stats/aggregates.py
@@ -54,7 +54,7 @@ def __init__(self, expression, percentiles, continuous=True, **extra):
         else:
             extra['function'] = 'PERCENTILE_DISC'
 
-        if six.PY2:
-            super(Percentile, self).__init__(expression, percentiles=percentiles, **extra)
-        else:
+        if six.PY3:
             super().__init__(expression, percentiles=percentiles, **extra)
+        else:
+            super(Percentile, self).__init__(expression, percentiles=percentiles, **extra)
diff --git a/postgres_stats/functions.py b/postgres_stats/functions.py
index aba97cc..fbf9433 100644
--- a/postgres_stats/functions.py
+++ b/postgres_stats/functions.py
@@ -100,9 +100,7 @@ class Extract(Func):
     template = "%(function)s(%(subfield)s FROM %(expressions)s)"
 
     def __init__(self, expression, subfield, **extra):
-        if six.PY2:
-            super(Extract, self).__init__(expression, subfield=subfield, **extra)
-        else:
+        if six.PY3:
             super().__init__(expression, subfield=subfield, **extra)
-
-
+        else:
+            super(Extract, self).__init__(expression, subfield=subfield, **extra)
diff --git a/requirements.txt b/requirements.txt
index 1097ee7..b275ec0 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,3 @@
 Django>=1.8.6
 psycopg2>=2.6.1
-six==1.10.0
+six>=1.0.0b1