diff --git a/packages/feature-learner/src/server/code.ts b/packages/feature-learner/src/server/code.ts
index 5d70353..27c64a3 100644
--- a/packages/feature-learner/src/server/code.ts
+++ b/packages/feature-learner/src/server/code.ts
@@ -71,7 +71,7 @@ export function codeRoutes(ctx: ServerContext): Feature["routes"] {
         const total = files.reduce((s, f) => s + f.size, 0);
         if (total > MAX_ZIP_BYTES) return json({ error: "this folder is too large to download as one zip" }, 413);
         const folder = r.code.dir.split("/").filter(Boolean).pop() ?? r.mod.id;
-        const data = zip(files.map((f) => ({ name: `${folder}/${f.path}`, data: readFileSync(f.abs), mtime: lstatSync(f.abs).mtime })));
+        const data = zip(files.map((f) => ({ name: `${folder}/${f.path}`, data: new Uint8Array(readFileSync(f.abs)), mtime: lstatSync(f.abs).mtime })));
         return new Response(data, {
           headers: { "Content-Type": "application/zip", "Content-Length": String(data.length), "Content-Disposition": contentDisposition(`${folder}.zip`) },
         });
diff --git a/packages/feature-learner/src/server/zip.ts b/packages/feature-learner/src/server/zip.ts
index 42f997e..d69671b 100644
--- a/packages/feature-learner/src/server/zip.ts
+++ b/packages/feature-learner/src/server/zip.ts
@@ -1,5 +1,5 @@
 /** Minimal ZIP writer (PKWARE APPNOTE 6.3): deflate or store per entry, CRC-32, UTF-8 names (flag bit 11). No ZIP64. */
-export interface ZipEntry { name: string; data: Uint8Array; mtime?: Date }
+export interface ZipEntry { name: string; data: Uint8Array<ArrayBuffer>; mtime?: Date }
 
 function dosTime(d: Date): { time: number; date: number } {
   const y = Math.max(1980, d.getFullYear());
@@ -9,9 +9,9 @@ function dosTime(d: Date): { time: number; date: number } {
   };
 }
 
-export function zip(entries: ZipEntry[]): Uint8Array {
+export function zip(entries: ZipEntry[]): Uint8Array<ArrayBuffer> {
   const enc = new TextEncoder();
-  const locals: Uint8Array[] = [];
+  const locals: Uint8Array<ArrayBuffer>[] = [];
   const centrals: Uint8Array[] = [];
   let offset = 0;
   for (const e of entries) {