diff --git a/packages/core-components/src/components/AlertDisplay/AlertDisplay.test.tsx b/packages/core-components/src/components/AlertDisplay/AlertDisplay.test.tsx
index bff018cc49..d21adf1479 100644
--- a/packages/core-components/src/components/AlertDisplay/AlertDisplay.test.tsx
+++ b/packages/core-components/src/components/AlertDisplay/AlertDisplay.test.tsx
@@ -214,6 +214,39 @@ describe('<AlertDisplay />', () => {
       expect(queryByText('transient message')).not.toBeInTheDocument();
       jest.useRealTimers();
     });
+
+    it('renders 3 different messages with overlapping timeout', async () => {
+      jest.useFakeTimers();
+      const { queryByText } = await renderInTestApp(
+        <TestApiProvider apis={apis}>
+          <AlertDisplay transientTimeoutMs={1500} />
+        </TestApiProvider>,
+      );
+
+      // 3 messages stacked with 1.5s each, display times: 0-1.5, 1.5-3, 3-4.5
+
+      // 0s in, only message 1
+      expect(queryByText('transient message one')).toBeInTheDocument();
+
+      // 1s in, message 1 still shown, message 2 added in background
+      act(() => jest.advanceTimersByTime(1000));
+      expect(queryByText('transient message one')).toBeInTheDocument();
+      expect(queryByText('(1 older message)')).toBeInTheDocument();
+
+      // 2s in, message 2 now shown, message 3 added
+      act(() => jest.advanceTimersByTime(1000));
+      expect(queryByText('transient message two')).toBeInTheDocument();
+      expect(queryByText('(1 older message)')).toBeInTheDocument();
+
+      // 3.5s in, message 3 now shown
+      act(() => jest.advanceTimersByTime(1500));
+      expect(queryByText('transient message three')).toBeInTheDocument();
+
+      // 5s in, all messages gone
+      act(() => jest.advanceTimersByTime(1500));
+      expect(queryByText('transient message three')).not.toBeInTheDocument();
+      jest.useRealTimers();
+    });
   });
 
   describe('with multiple messages of mixed display', () => {
diff --git a/packages/core-components/src/components/AlertDisplay/AlertDisplay.tsx b/packages/core-components/src/components/AlertDisplay/AlertDisplay.tsx
index e85887c174..fe20b1d66d 100644
--- a/packages/core-components/src/components/AlertDisplay/AlertDisplay.tsx
+++ b/packages/core-components/src/components/AlertDisplay/AlertDisplay.tsx
@@ -19,6 +19,7 @@ import Snackbar from '@material-ui/core/Snackbar';
 import Typography from '@material-ui/core/Typography';
 import CloseIcon from '@material-ui/icons/Close';
 import { Alert } from '@material-ui/lab';
+import { useIsMounted } from '@react-hookz/web';
 import pluralize from 'pluralize';
 import React, { useEffect, useState } from 'react';
 
@@ -62,6 +63,7 @@ export type AlertDisplayProps = {
 export function AlertDisplay(props: AlertDisplayProps) {
   const [messages, setMessages] = useState<Array<AlertMessage>>([]);
   const alertApi = useApi(alertApiRef);
+  const isMounted = useIsMounted();
 
   const {
     anchorOrigin = { vertical: 'top', horizontal: 'center' },
@@ -82,13 +84,14 @@ export function AlertDisplay(props: AlertDisplayProps) {
   useEffect(() => {
     const [current] = messages;
     if (current && current.display === 'transient') {
-      const timer = setTimeout(() => {
-        setMessages(msgs => msgs.filter(msg => msg !== current));
+      setTimeout(() => {
+        if (isMounted()) {
+          setMessages(msgs => msgs.filter(msg => msg !== current));
+        }
       }, timeoutMs);
-      return () => clearTimeout(timer);
     }
     return undefined;
-  }, [messages, timeoutMs]);
+  }, [messages, timeoutMs, isMounted]);
 
   if (messages.length === 0) {
     return null;