diff --git a/packages/core-components/src/components/AlertDisplay/AlertDisplay.test.tsx b/packages/core-components/src/components/AlertDisplay/AlertDisplay.test.tsx
index d21adf1479..b75f773f90 100644
--- a/packages/core-components/src/components/AlertDisplay/AlertDisplay.test.tsx
+++ b/packages/core-components/src/components/AlertDisplay/AlertDisplay.test.tsx
@@ -247,6 +247,43 @@ describe('<AlertDisplay />', () => {
       expect(queryByText('transient message three')).not.toBeInTheDocument();
       jest.useRealTimers();
     });
+
+    it('renders 3 different messages with overlapping timeout and manual removal', 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();
+
+      // manually remove message 1
+      fireEvent.click(screen.getByTestId('error-button-close'));
+      expect(screen.getByText('transient message two')).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();
+
+      // 3s in, message 3 now shown
+      act(() => jest.advanceTimersByTime(1500));
+      expect(queryByText('transient message three')).toBeInTheDocument();
+
+      // 4s 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 fe20b1d66d..f1021b1f8b 100644
--- a/packages/core-components/src/components/AlertDisplay/AlertDisplay.tsx
+++ b/packages/core-components/src/components/AlertDisplay/AlertDisplay.tsx
@@ -19,7 +19,6 @@ 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';
 
@@ -63,7 +62,6 @@ 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' },
@@ -81,24 +79,25 @@ export function AlertDisplay(props: AlertDisplayProps) {
     };
   }, [alertApi]);
 
+  const [firstMessage] = messages;
+
   useEffect(() => {
-    const [current] = messages;
-    if (current && current.display === 'transient') {
-      setTimeout(() => {
-        if (isMounted()) {
-          setMessages(msgs => msgs.filter(msg => msg !== current));
-        }
+    if (firstMessage && firstMessage.display === 'transient') {
+      const timeout = setTimeout(() => {
+        setMessages(msgs => {
+          const newMsgs = msgs.filter(msg => msg !== firstMessage);
+          return newMsgs.length === msgs.length ? msgs : newMsgs;
+        });
       }, timeoutMs);
+      return () => clearTimeout(timeout);
     }
     return undefined;
-  }, [messages, timeoutMs, isMounted]);
+  }, [firstMessage, timeoutMs]);
 
   if (messages.length === 0) {
     return null;
   }
 
-  const [firstMessage] = messages;
-
   const handleClose = () => {
     setMessages(msgs => msgs.filter(msg => msg !== firstMessage));
   };