diff --git a/bijoe/engine.py b/bijoe/engine.py
index a8a7b89..8838f59 100644
--- a/bijoe/engine.py
+++ b/bijoe/engine.py
@@ -209,7 +209,8 @@ class JSONDimensions(object):
             return []
         if not self.__cache:
             with self.engine.get_cursor() as cursor:
-                sql = 'select distinct jsonb_object_keys(json_data) as a from formdata order by a'
+                sql = ('select distinct jsonb_object_keys(%s) as a from formdata order by a'
+                       % self.engine_cube.json_field)
                 cursor.execute(sql)
                 self.__cache = [row[0] for row in cursor.fetchall()]
         return self.__cache