diff --git a/src/utils.ts b/src/utils.ts
index 76e1e34..626aaf2 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -23,6 +23,6 @@ export function isString (value: unknown): value is string {
   return typeof value === 'string' || value instanceof String;
 }
 
-export function flushPromises () {
+export async function flushPromises () {
   return new Promise((resolve, _reject) => setImmediate(resolve));
 }