diff --git a/src/karlkoder_codec.js b/src/karlkoder_codec.js
index da694f7..71bf407 100644
--- a/src/karlkoder_codec.js
+++ b/src/karlkoder_codec.js
@@ -1,3 +1,5 @@
+import { readFileToBytes, strToBytes } from "./utils.js";
+
 const KEYWORDS = ["asset", "code"];
 const MIN_KW_LENGTH = Math.min(...KEYWORDS.map((x) => x.length));
 const MAX_KW_LENGTH = Math.max(...KEYWORDS.map((x) => x.length));
@@ -8,10 +10,6 @@ function isKeyword(buffer) {
     return KEYWORDS.includes(kw);
 }
 
-function strToBytes(str) {
-    return str.split("").map((x) => x.charCodeAt(0));
-}
-
 export class KarlkoderCodec {
     static async en(name, code, assets) {
         const ret = [];
@@ -25,7 +23,7 @@ export class KarlkoderCodec {
             ret.push(...strToBytes(";"));
             ret.push(...strToBytes(asset.name));
             ret.push(...strToBytes(asset.file.type));
-            ret.push(...await asset.file.bytes());
+            ret.push(...await readFileToBytes(asset.file));
         }
         ret.push(...strToBytes("code"));
         ret.push(...strToBytes(name.length.toString()));
diff --git a/src/utils.js b/src/utils.js
index 5f5dd43..4e71c0c 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -18,3 +18,16 @@ export function minifyJs(code) {
         .filter((line) => line.length > 0)
         .join("\n");
 }
+
+export function strToBytes(str) {
+    return str.split("").map((x) => x.charCodeAt(0));
+}
+
+export function readFileToBytes(file) {
+    return new Promise((resolve, reject) => {
+        const reader = new FileReader();
+        reader.readAsArrayBuffer(file);
+        reader.onload = () => resolve(new Uint8Array(reader.result));
+        reader.onerror = () => reject(reader.error);
+    });
+}