diff --git a/README.md b/README.md
index cfb60c7..2ebe7d8 100644
--- a/README.md
+++ b/README.md
@@ -161,22 +161,37 @@ assertEquals(await promiseState(waiter1), "fulfilled");
 assertEquals(await promiseState(waiter2), "fulfilled");
 ```
 
-### promiseState
+### peekPromiseState
 
-`promiseState` is used to determine the state of the promise. Mainly for testing
-purpose.
+`peekPromiseState` is used to determine the state of the promise. Mainly for
+testing purpose.
 
 ```typescript
-import { promiseState } from "@core/asyncutil/promise-state";
+import { peekPromiseState } from "@core/asyncutil/peek-promise-state";
 
 const p1 = Promise.resolve("Resolved promise");
-console.log(await promiseState(p1)); // fulfilled
+console.log(await peekPromiseState(p1)); // fulfilled
 
 const p2 = Promise.reject("Rejected promise").catch(() => undefined);
-console.log(await promiseState(p2)); // rejected
+console.log(await peekPromiseState(p2)); // rejected
 
 const p3 = new Promise(() => undefined);
-console.log(await promiseState(p3)); // pending
+console.log(await peekPromiseState(p3)); // pending
+```
+
+Use `flushPromises` to wait all pending promises to resolve.
+
+```typescript
+import { flushPromises } from "@core/asyncutil/flush-promises";
+import { peekPromiseState } from "@core/asyncutil/peek-promise-state";
+
+const p = Promise.resolve<void>(undefined)
+  .then(() => {})
+  .then(() => {});
+
+console.log(await peekPromiseState(p)); // pending
+await flushPromises();
+console.log(await peekPromiseState(p)); // fulfilled
 ```
 
 ### Queue/Stack