diff --git a/src/asar.ts b/src/asar.ts
index 2d1b5cb..6b380d2 100644
--- a/src/asar.ts
+++ b/src/asar.ts
@@ -2,7 +2,12 @@ import * as path from 'path';
 import minimatch from 'minimatch';
 
 import fs from './wrapped-fs';
-import { Filesystem, FilesystemEntry } from './filesystem';
+import {
+  Filesystem,
+  FilesystemDirectoryEntry,
+  FilesystemEntry,
+  FilesystemLinkEntry,
+} from './filesystem';
 import * as disk from './disk';
 import { crawl as crawlFilesystem, determineFileType } from './crawlfs';
 import { IOptions } from 'glob';
@@ -192,7 +197,11 @@ export function getRawHeader(archivePath: string) {
   return disk.readArchiveHeaderSync(archivePath);
 }
 
-export function listPackage(archivePath: string, options: { isPack: boolean }) {
+export interface ListOptions {
+  isPack: boolean;
+}
+
+export function listPackage(archivePath: string, options: ListOptions) {
   return disk.readFilesystemSync(archivePath).listFiles(options);
 }
 
@@ -272,6 +281,18 @@ export function uncacheAll() {
   disk.uncacheAll();
 }
 
+// Legacy type exports to maintain compatibility with pre-TypeScript rewrite
+// (https://github.com/electron/asar/blob/50b0c62e5b24c3d164687e6470b8658e09b09eea/lib/index.d.ts)
+// These don't match perfectly and are technically still a breaking change but they're close enough
+// to keep _most_ build pipelines out there from breaking.
+export { EntryMetadata } from './filesystem';
+export { InputMetadata, DirectoryRecord, FileRecord, ArchiveHeader } from './disk';
+export type InputMetadataType = 'directory' | 'file' | 'link';
+export type DirectoryMetadata = FilesystemDirectoryEntry;
+export type FileMetadata = FilesystemEntry;
+export type LinkMetadata = FilesystemLinkEntry;
+
+// Export everything in default, too
 export default {
   createPackage,
   createPackageWithOptions,
diff --git a/src/disk.ts b/src/disk.ts
index 57e2133..ecb7263 100644
--- a/src/disk.ts
+++ b/src/disk.ts
@@ -1,9 +1,8 @@
 import * as path from 'path';
 import fs from './wrapped-fs';
 import { Pickle } from './pickle';
-import { Filesystem, FilesystemEntry, FilesystemFileEntry } from './filesystem';
+import { Filesystem, FilesystemFileEntry } from './filesystem';
 import { CrawledFileType } from './crawlfs';
-import { Stats } from 'fs';
 
 let filesystemCache: Record<string, Filesystem | undefined> = Object.create(null);
 
@@ -80,7 +79,27 @@ export async function writeFilesystem(
   return writeFileListToStream(dest, filesystem, out, fileList, metadata);
 }
 
-export function readArchiveHeaderSync(archivePath: string) {
+export interface FileRecord extends FilesystemFileEntry {
+  integrity: {
+    hash: string;
+    algorithm: 'SHA256';
+    blocks: string[];
+    blockSize: number;
+  };
+}
+
+export type DirectoryRecord = {
+  files: Record<string, DirectoryRecord | FileRecord>;
+};
+
+export type ArchiveHeader = {
+  // The JSON parsed header string
+  header: DirectoryRecord;
+  headerString: string;
+  headerSize: number;
+};
+
+export function readArchiveHeaderSync(archivePath: string): ArchiveHeader {
   const fd = fs.openSync(archivePath, 'r');
   let size: number;
   let headerBuf: Buffer;
diff --git a/src/filesystem.ts b/src/filesystem.ts
index 577beea..c4d68d5 100644
--- a/src/filesystem.ts
+++ b/src/filesystem.ts
@@ -11,22 +11,25 @@ const UINT32_MAX = 2 ** 32 - 1;
 
 const pipeline = promisify(stream.pipeline);
 
-export type FilesystemDirectoryEntry = {
-  files: Record<string, FilesystemEntry>;
+export type EntryMetadata = {
   unpacked?: boolean;
 };
 
+export type FilesystemDirectoryEntry = {
+  files: Record<string, FilesystemEntry>;
+} & EntryMetadata;
+
 export type FilesystemFileEntry = {
   unpacked: boolean;
   executable: boolean;
   offset: string;
   size: number;
   integrity: FileIntegrity;
-};
+} & EntryMetadata;
 
 export type FilesystemLinkEntry = {
   link: string;
-};
+} & EntryMetadata;
 
 export type FilesystemEntry = FilesystemDirectoryEntry | FilesystemFileEntry | FilesystemLinkEntry;