diff --git a/docs/ja/reference/function/after.md b/docs/ja/reference/function/after.md
index 8d907c1b..5089ecd0 100644
--- a/docs/ja/reference/function/after.md
+++ b/docs/ja/reference/function/after.md
@@ -8,7 +8,10 @@
 ## インターフェース
 
 ```typescript
-function after<F extends (...args: any[]) => any>(n: number, func: F): F;
+function after<F extends (...args: any[]) => any>(
+  n: number,
+  func: F
+): (...args: Parameters<F>) => ReturnType<F> | undefined;
 ```
 
 ### パラメータ
@@ -18,7 +21,7 @@ function after<F extends (...args: any[]) => any>(n: number, func: F): F;
 
 ### 戻り値
 
-(`F`): 新しい関数を返します。この関数は以下の機能を持ちます：
+(`(...args: Parameters<F>) => ReturnType<F> | undefined`): 新しい関数を返します。この関数は以下の機能を持ちます：
 
 - 呼び出された回数を追跡します。
 - `n`回目の呼び出しから`func`を呼び出します。
diff --git a/docs/ko/reference/function/after.md b/docs/ko/reference/function/after.md
index 7aa8001d..6a0504c8 100644
--- a/docs/ko/reference/function/after.md
+++ b/docs/ko/reference/function/after.md
@@ -8,7 +8,10 @@
 ## 인터페이스
 
 ```typescript
-function after<F extends (...args: any[]) => any>(n: number, func: F): F;
+function after<F extends (...args: any[]) => any>(
+  n: number,
+  func: F
+): (...args: Parameters<F>) => ReturnType<F> | undefined;
 ```
 
 ### 파라미터
@@ -18,7 +21,7 @@ function after<F extends (...args: any[]) => any>(n: number, func: F): F;
 
 ### 반환 값
 
-(`F`): 새로운 함수를 반환해요. 이 함수는 다음과 같은 기능을 가져요.
+(`(...args: Parameters<F>) => ReturnType<F> | undefined`): 새로운 함수를 반환해요. 이 함수는 다음과 같은 기능을 가져요.
 
 - 호출된 횟수를 추적해요.
 - `n`번째 호출부터 `func`을 호출해요.
diff --git a/docs/reference/function/after.md b/docs/reference/function/after.md
index 638c0eb5..4bb34d5d 100644
--- a/docs/reference/function/after.md
+++ b/docs/reference/function/after.md
@@ -8,7 +8,10 @@ The is particularly useful for scenarios involving events or asynchronous operat
 ## Signature
 
 ```typescript
-function after<F extends (...args: any[]) => any>(n: number, func: F): F;
+function after<F extends (...args: any[]) => any>(
+  n: number,
+  func: F
+): (...args: Parameters<F>) => ReturnType<F> | undefined;
 ```
 
 ### Parameters
@@ -18,7 +21,7 @@ function after<F extends (...args: any[]) => any>(n: number, func: F): F;
 
 ### Returns
 
-(`F`): A new function that:
+(`(...args: Parameters<F>) => ReturnType<F> | undefined`): A new function that:
 
 - Tracks the number of calls.
 - Invokes `func` starting from the `n`-th call.
diff --git a/docs/zh_hans/reference/function/after.md b/docs/zh_hans/reference/function/after.md
index 17f27583..90fd2fb1 100644
--- a/docs/zh_hans/reference/function/after.md
+++ b/docs/zh_hans/reference/function/after.md
@@ -8,7 +8,10 @@
 ## 签名
 
 ```typescript
-function after<F extends (...args: any[]) => any>(n: number, func: F): F;
+function after<F extends (...args: any[]) => any>(
+  n: number,
+  func: F
+): (...args: Parameters<F>) => ReturnType<F> | undefined;
 ```
 
 ### 参数
@@ -18,7 +21,7 @@ function after<F extends (...args: any[]) => any>(n: number, func: F): F;
 
 ### 返回值
 
-(`F`): 一个新函数，它：
+(`(...args: Parameters<F>) => ReturnType<F> | undefined`): 一个新函数，它：
 
 - 跟踪调用次数。
 - 从第 `n` 次调用开始调用 `func`。
diff --git a/src/compat/_internal/isKey.ts b/src/compat/_internal/isKey.ts
index 439a3414..3de621d6 100644
--- a/src/compat/_internal/isKey.ts
+++ b/src/compat/_internal/isKey.ts
@@ -18,7 +18,7 @@ const regexIsPlainProp = /^\w*$/;
  * isKey('a.b', { a: { b: 2 } });
  * // => false
  */
-export function isKey(value?: unknown, object?: unknown): boolean {
+export function isKey(value?: unknown, object?: unknown): value is PropertyKey {
   if (Array.isArray(value)) {
     return false;
   }
diff --git a/src/compat/array/orderBy.ts b/src/compat/array/orderBy.ts
index 09f0b0ae..14918f78 100644
--- a/src/compat/array/orderBy.ts
+++ b/src/compat/array/orderBy.ts
@@ -107,7 +107,7 @@ export function orderBy<T>(
     }
 
     // If criterion is not key, it has possibility to be a deep path. So we have to prepare both cases.
-    return { key: criterion, path: toPath(criterion as string) } as const;
+    return { key: criterion, path: toPath(criterion) };
   });
 
   // Array.prototype.sort() always shifts the `undefined` values to the end of the array. So we have to prevent it by using a wrapper object.
diff --git a/src/function/after.ts b/src/function/after.ts
index ce362645..3e9ee9be 100644
--- a/src/function/after.ts
+++ b/src/function/after.ts
@@ -8,7 +8,7 @@
  * @template F - The type of the function to be invoked.
  * @param {number} n - The number of calls required for `func` to execute.
  * @param {F} func - The function to be invoked.
- * @returns {F} - A new function that:
+ * @returns {(...args: Parameters<F>) => ReturnType<F> | undefined} - A new function that:
  * - Tracks the number of calls.
  * - Invokes `func` starting from the `n`-th call.
  * - Returns `undefined` if fewer than `n` calls have been made.
@@ -27,16 +27,19 @@
  * afterFn()
  */
 
-export function after<F extends (...args: any[]) => any>(n: number, func: F): F {
+export function after<F extends (...args: any[]) => any>(
+  n: number,
+  func: F
+): (...args: Parameters<F>) => ReturnType<F> | undefined {
   if (!Number.isInteger(n) || n < 0) {
     throw new Error(`n must be a non-negative integer.`);
   }
 
   let counter = 0;
-  return ((...args: Parameters<F>) => {
+  return (...args: Parameters<F>) => {
     if (++counter >= n) {
       return func(...args);
     }
     return undefined;
-  }) as F;
+  };
 }
diff --git a/src/promise/withTimeout.ts b/src/promise/withTimeout.ts
index eb920a11..0e5dfec5 100644
--- a/src/promise/withTimeout.ts
+++ b/src/promise/withTimeout.ts
@@ -26,5 +26,5 @@ import { timeout } from './timeout.ts';
  * }
  */
 export async function withTimeout<T>(run: () => Promise<T>, ms: number): Promise<T> {
-  return Promise.race([run(), timeout(ms) as T]);
+  return Promise.race([run(), timeout(ms)]);
 }