diff --git a/pydruid/client.py b/pydruid/client.py
index 2a245bc1..cd5f5f5e 100755
--- a/pydruid/client.py
+++ b/pydruid/client.py
@@ -213,11 +213,11 @@ def build_query(self, args):
             if key == 'aggregations':
                 query_dict[key] = build_aggregators(val)
             elif key == 'post_aggregations':
-                query_dict['postAggregations'] = build_post_aggregators(val)
+                query_dict['postAggregations'] = Postaggregator.build_post_aggregators(val)
             elif key == 'datasource':
                 query_dict['dataSource'] = val
             elif key == "filter":
-                query_dict[key] = build_filter(val)
+                query_dict[key] = Filter.build_filter(val)
             else:
                 query_dict[key] = val
 
diff --git a/pydruid/utils/filters.py b/pydruid/utils/filters.py
index ecfde90c..053bb4b1 100644
--- a/pydruid/utils/filters.py
+++ b/pydruid/utils/filters.py
@@ -53,6 +53,10 @@ def __or__(self, x):
     def __invert__(self):
         return Filter(type="not", field=self.filter['filter'])
 
+    @staticmethod
+    def build_filter(filter_obj):
+        return filter_obj.filter['filter']
+
 
 class Dimension:
     def __init__(self, dim):
@@ -61,6 +65,3 @@ def __init__(self, dim):
     def __eq__(self, other):
         return Filter(dimension=self.dimension, value=other)
 
-
-def build_filter(filter_obj):
-    return filter_obj.filter['filter']
diff --git a/pydruid/utils/postaggregator.py b/pydruid/utils/postaggregator.py
index c1837bc4..c6dd5e3a 100644
--- a/pydruid/utils/postaggregator.py
+++ b/pydruid/utils/postaggregator.py
@@ -43,6 +43,15 @@ def __div__(self, other):
     def fields(self, other):
         return [self.post_aggregator, other.post_aggregator]
 
+    @staticmethod
+    def build_post_aggregators(postaggs):
+        def rename_postagg(new_name, post_aggregator):
+            post_aggregator['name'] = new_name
+            return post_aggregator
+
+        return [rename_postagg(new_name, postagg.post_aggregator)
+                for (new_name, postagg) in postaggs.iteritems()]
+
 
 class Field(Postaggregator):
     def __init__(self, name):
@@ -62,13 +71,3 @@ def __init__(self, value, output_name=None):
         Postaggregator.__init__(self, None, None, name)
         self.post_aggregator = {
             'type': 'constant', 'name': name, 'value': value}
-
-
-def build_post_aggregators(postaggs):
-    return [rename_postagg(new_name, postagg.post_aggregator)
-            for (new_name, postagg) in postaggs.iteritems()]
-
-
-def rename_postagg(new_name, post_aggregator):
-    post_aggregator['name'] = new_name
-    return post_aggregator