diff --git a/src/components/views/rooms/RoomUpgradeWarningBar.js b/src/components/views/rooms/RoomUpgradeWarningBar.js
index 531428198e..877cfb39d7 100644
--- a/src/components/views/rooms/RoomUpgradeWarningBar.js
+++ b/src/components/views/rooms/RoomUpgradeWarningBar.js
@@ -1,5 +1,5 @@
 /*
-Copyright 2018 New Vector Ltd
+Copyright 2018-2020 New Vector Ltd
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -28,6 +28,11 @@ export default class RoomUpgradeWarningBar extends React.Component {
         recommendation: PropTypes.object.isRequired,
     };
 
+    constructor(props) {
+        super(props);
+        this.state = {};
+    }
+
     componentDidMount() {
         const tombstone = this.props.room.currentState.getStateEvents("m.room.tombstone", "");
         this.setState({upgraded: tombstone && tombstone.getContent().replacement_room});
@@ -35,6 +40,13 @@ export default class RoomUpgradeWarningBar extends React.Component {
         MatrixClientPeg.get().on("RoomState.events", this._onStateEvents);
     }
 
+    componentWillUnmount() {
+        const cli = MatrixClientPeg.get();
+        if (cli) {
+            cli.removeListener("RoomState.events", this._onStateEvents);
+        }
+    }
+
     _onStateEvents = (event, state) => {
         if (!this.props.room || event.getRoomId() !== this.props.room.roomId) {
             return;