diff --git a/app/src/util/useListener.ts b/app/src/util/useListener.ts
index 9ad23358..9372d4c2 100644
--- a/app/src/util/useListener.ts
+++ b/app/src/util/useListener.ts
@@ -4,7 +4,7 @@ export function useWindowEvent<K extends keyof WindowEventMap>(
   type: K,
   listener: (this: Window, ev: WindowEventMap[K]) => any,
   deps: DependencyList = []
-) {
+): void {
   useEffect(() => {
     window.addEventListener(type, listener);
     return () => window.removeEventListener(type, listener);
@@ -15,7 +15,7 @@ export function useDocumentEvent<K extends keyof DocumentEventMap>(
   type: K,
   listener: (this: Document, ev: DocumentEventMap[K]) => any,
   deps: DependencyList = []
-) {
+): void {
   useEffect(() => {
     document.addEventListener(type, listener);
     return () => document.removeEventListener(type, listener);