diff --git a/redash/query_runner/db2.py b/redash/query_runner/db2.py
index 3253cee0b9..7413189459 100644
--- a/redash/query_runner/db2.py
+++ b/redash/query_runner/db2.py
@@ -3,7 +3,7 @@
 import logging
 
 from redash.query_runner import *
-from redash.utils import JSONEncoder
+from redash.utils import json_dumps
 
 logger = logging.getLogger(__name__)
 
@@ -129,7 +129,7 @@ def run_query(self, query, user):
 
                 data = {'columns': columns, 'rows': rows}
                 error = None
-                json_data = json.dumps(data, cls=JSONEncoder)
+                json_data = json_dumps(data)
             else:
                 error = 'Query completed but it returned no data.'
                 json_data = None
diff --git a/redash/query_runner/kylin.py b/redash/query_runner/kylin.py
index a9f5d1fdb4..261fa3f5e0 100644
--- a/redash/query_runner/kylin.py
+++ b/redash/query_runner/kylin.py
@@ -1,12 +1,11 @@
 import os
-import json
 import logging
 import requests
 from requests.auth import HTTPBasicAuth
 
 from redash import settings
 from redash.query_runner import *
-from redash.utils import JSONEncoder
+from redash.utils import json_dumps
 
 logger = logging.getLogger(__name__)
 
@@ -102,7 +101,7 @@ def run_query(self, query, user):
         columns = self.get_columns(data['columnMetas'])
         rows = self.get_rows(columns, data['results'])
 
-        return json.dumps({'columns': columns, 'rows': rows}), None
+        return json_dumps({'columns': columns, 'rows': rows}), None
 
     def get_schema(self, get_stats=False):
         url = self.configuration['url']
diff --git a/redash/query_runner/rockset.py b/redash/query_runner/rockset.py
index 5d0d30d99d..eafb41c822 100644
--- a/redash/query_runner/rockset.py
+++ b/redash/query_runner/rockset.py
@@ -1,8 +1,6 @@
 import requests
-import os
 from redash.query_runner import *
-from redash.utils import JSONEncoder
-import json
+from redash.utils import json_dumps
 
 
 def _get_type(value):
@@ -96,7 +94,7 @@ def run_query(self, query, user):
             columns = []
             for k in rows[0]:
                 columns.append({'name': k, 'friendly_name': k, 'type': _get_type(rows[0][k])})
-        data = json.dumps({'columns': columns, 'rows': rows}, cls=JSONEncoder)
+        data = json_dumps({'columns': columns, 'rows': rows})
         return data, None
 
 
diff --git a/redash/serializers.py b/redash/serializers.py
index 449e882a22..155e02620c 100644
--- a/redash/serializers.py
+++ b/redash/serializers.py
@@ -8,7 +8,6 @@
 from flask_login import current_user
 
 from redash import models
-from redash.handlers.query_results import run_query_sync
 from redash.permissions import has_access, view_only
 from redash.utils import json_loads
 from redash.models.parameterized_query import ParameterizedQuery
@@ -31,6 +30,9 @@ def public_widget(widget):
         # make sure the widget's query has a latest_query_data_id that is
         # not null so public dashboards work
         if q.latest_query_data_id is None:
+            # this import is inline since it triggers a circular
+            # import otherwise
+            from redash.handlers.query_results import run_query_sync
             run_query_sync(q.data_source, {}, q.query_text)
 
         query_data = q.latest_query_data.to_dict()