diff --git a/index.d.ts b/index.d.ts
index c643aa7..67fdd68 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -292,7 +292,7 @@ export interface AxiosStatic extends AxiosInstance {
   Axios: typeof Axios;
   AxiosError: typeof AxiosError;
   readonly VERSION: string;
-  isCancel(value: any): boolean;
+  isCancel(value: any): value is Cancel;
   all<T>(values: Array<T | Promise<T>>): Promise<T[]>;
   spread<T, R>(callback: (...args: T[]) => R): (array: T[]) => R;
   isAxiosError<T = any, D = any>(payload: any): payload is AxiosError<T, D>;