diff --git a/superset-frontend/src/components/LastUpdated/index.tsx b/superset-frontend/src/components/LastUpdated/index.tsx
index 7556d5a9a72c9..dc55957300ed3 100644
--- a/superset-frontend/src/components/LastUpdated/index.tsx
+++ b/superset-frontend/src/components/LastUpdated/index.tsx
@@ -17,14 +17,14 @@
  * under the License.
  */
 import React, { useEffect, useState, FunctionComponent } from 'react';
-import moment from 'moment';
+import moment, { Moment, MomentInput } from 'moment';
 import { t, styled } from '@superset-ui/core';
 import Icon from 'src/components/Icon';
 
 const REFRESH_INTERVAL = 60000; // every minute
 
 interface LastUpdatedProps {
-  updatedAt: string | Date | number;
+  updatedAt: MomentInput;
   update?: React.MouseEventHandler<SVGSVGElement>;
 }
 moment.updateLocale('en', {
@@ -56,7 +56,7 @@ export const LastUpdated: FunctionComponent<LastUpdatedProps> = ({
   updatedAt,
   update,
 }) => {
-  const [timeSince, setTimeSince] = useState<moment.Moment>(moment(updatedAt));
+  const [timeSince, setTimeSince] = useState<Moment>(moment(updatedAt));
 
   useEffect(() => {
     setTimeSince(() => moment(updatedAt));
diff --git a/superset-frontend/src/views/CRUD/alert/AlertList.tsx b/superset-frontend/src/views/CRUD/alert/AlertList.tsx
index 13405d4a3387f..862ee1ea6aded 100644
--- a/superset-frontend/src/views/CRUD/alert/AlertList.tsx
+++ b/superset-frontend/src/views/CRUD/alert/AlertList.tsx
@@ -409,10 +409,7 @@ function AlertList({
         buttons={subMenuButtons}
       >
         <RefreshContainer>
-          <LastUpdated
-            updatedAt={lastFetched || ''}
-            update={() => refreshData()}
-          />
+          <LastUpdated updatedAt={lastFetched} update={() => refreshData()} />
         </RefreshContainer>
       </SubMenu>
       <AlertReportModal