diff --git a/superset/assets/src/visualizations/Calendar/Calendar.js b/superset/assets/src/visualizations/Calendar/Calendar.js
index 5b7bfe755ea..6b7aadae38d 100644
--- a/superset/assets/src/visualizations/Calendar/Calendar.js
+++ b/superset/assets/src/visualizations/Calendar/Calendar.js
@@ -95,7 +95,7 @@ function Calendar(element, props) {
     cal.init({
       start: UTCTS(data.start),
       data: timestamps,
-      itemSelector: calContainer[0][0],
+      itemSelector: calContainer.node(),
       legendVerticalPosition: 'top',
       cellSize,
       cellPadding,
diff --git a/superset/viz.py b/superset/viz.py
index e3e891ac07f..a3c5f06b94e 100644
--- a/superset/viz.py
+++ b/superset/viz.py
@@ -789,10 +789,13 @@ class CalHeatmapViz(BaseViz):
         data = {}
         records = df.to_dict('records')
         for metric in self.metric_labels:
-            data[metric] = {
-                str(obj[DTTM_ALIAS] / 10**9): obj.get(metric)
-                for obj in records
-            }
+            values = {}
+            for obj in records:
+                v = obj[DTTM_ALIAS]
+                if hasattr(v, 'value'):
+                    v = v.value
+                values[str(v / 10**9)] = obj.get(metric)
+            data[metric] = values
 
         start, end = utils.get_since_until(form_data.get('time_range'),
                                            form_data.get('since'),