diff --git a/superset/assets/javascripts/dashboard/components/GridCell.jsx b/superset/assets/javascripts/dashboard/components/GridCell.jsx
index 26d8eeb6eadc4..b0c86ad0c4990 100644
--- a/superset/assets/javascripts/dashboard/components/GridCell.jsx
+++ b/superset/assets/javascripts/dashboard/components/GridCell.jsx
@@ -12,7 +12,7 @@ const propTypes = {
   datasource: PropTypes.object,
   isLoading: PropTypes.bool,
   isCached: PropTypes.bool,
-  cachedDttm: PropTypes.number,
+  cachedDttm: PropTypes.string,
   isExpanded: PropTypes.bool,
   widgetHeight: PropTypes.number,
   widgetWidth: PropTypes.number,
diff --git a/superset/assets/javascripts/dashboard/components/SliceHeader.jsx b/superset/assets/javascripts/dashboard/components/SliceHeader.jsx
index 8360017d44fa2..4e8a33537c9a2 100644
--- a/superset/assets/javascripts/dashboard/components/SliceHeader.jsx
+++ b/superset/assets/javascripts/dashboard/components/SliceHeader.jsx
@@ -12,7 +12,7 @@ const propTypes = {
   exportCSVUrl: PropTypes.string,
   isExpanded: PropTypes.bool,
   isCached: PropTypes.bool,
-  cachedDttm: PropTypes.number,
+  cachedDttm: PropTypes.string,
   formDataExtra: PropTypes.object,
   removeSlice: PropTypes.func,
   updateSliceName: PropTypes.func,