diff --git a/src/me/topchetoeu/jscript/js/lib.d.ts b/src/me/topchetoeu/jscript/js/lib.d.ts
index df95570..490ea1a 100644
--- a/src/me/topchetoeu/jscript/js/lib.d.ts
+++ b/src/me/topchetoeu/jscript/js/lib.d.ts
@@ -482,6 +482,27 @@ interface PromiseConstructor {
     allSettled<T extends any[]>(...promises: T): Promise<[...{ [P in keyof T]: PromiseResult<Awaited<T[P]>>}]>;
 }
 
+interface FileStat {
+    type: 'file' | 'folder';
+    mode: 'r' | 'rw';
+}
+interface File {
+    readonly pointer: Promise<number>;
+    readonly length: Promise<number>;
+    read(buff: number[], n: number): Promise<number>;
+    write(buff: number[]): Promise<void>;
+    setPointer(val: number): Promise<void>;
+}
+interface Filesystem {
+    open(path: string, mode: 'r' | 'rw'): Promise<File>;
+    ls(path: string): AsyncIterableIterator<string>;
+    mkdir(path: string): Promise<void>;
+    mkfile(path: string): Promise<void>;
+    rm(path: string, recursive?: boolean): Promise<void>;
+    stat(path: string): Promise<FileStat>;
+    exists(path: string): Promise<boolean>;
+}
+
 declare var String: StringConstructor;
 //@ts-ignore
 declare const arguments: IArguments;
@@ -508,6 +529,7 @@ declare var Object: ObjectConstructor;
 declare var Symbol: SymbolConstructor;
 declare var Promise: PromiseConstructor;
 declare var Math: MathObject;
+declare var fs: Filesystem;
 
 declare var Error: ErrorConstructor;
 declare var RangeError: RangeErrorConstructor;