diff --git a/src/components/views/rooms/ReplyPreview.tsx b/src/components/views/rooms/ReplyPreview.tsx
index a3d018ec2d..41b3d2460c 100644
--- a/src/components/views/rooms/ReplyPreview.tsx
+++ b/src/components/views/rooms/ReplyPreview.tsx
@@ -42,7 +42,7 @@ interface IState {
 @replaceableComponent("views.rooms.ReplyPreview")
 export default class ReplyPreview extends React.Component<IProps, IState> {
     private unmounted = false;
-    private roomStoreToken: EventSubscription;
+    private readonly roomStoreToken: EventSubscription;
 
     constructor(props) {
         super(props);