diff --git a/package.json b/package.json
index 289b04f..da0c8ea 100644
--- a/package.json
+++ b/package.json
@@ -78,6 +78,7 @@
     "transform": {
       "^.+\\.(js|jsx|ts|tsx)$": "babel-jest"
     },
-    "testRegex": "/src/.*\\.spec\\.(js|ts|tsx)$"
+    "testRegex": "/src/.*\\.spec\\.(js|ts|tsx)$",
+    "testURL": "http://localhost/"
   }
 }
diff --git a/src/index.d.ts b/src/index.d.ts
index c425252..049a6e1 100644
--- a/src/index.d.ts
+++ b/src/index.d.ts
@@ -6,4 +6,4 @@
  * @param  interval  Number  Wait-between-retries interval, 50ms by default
  * @return  Promise  Promise to return a callback result
  */
-export default function waitForExpect(expectation: () => void, timeout?: number, interval?: number): any;
+export default function waitForExpect(expectation: () => void | Promise<void>, timeout?: number, interval?: number): any;
diff --git a/src/index.ts b/src/index.ts
index 350f7cf..8d81984 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -14,7 +14,7 @@ const defaults = {
  * @return  Promise  Promise to return a callback result
  */
 const waitForExpect = function waitForExpect(
-  expectation: () => void,
+  expectation: () => void | Promise<void>,
   timeout = defaults.timeout,
   interval = defaults.interval
 ) {