diff --git a/libsquoosh/src/index.js b/libsquoosh/src/index.js
index 93c1a895..dfd00cc4 100644
--- a/libsquoosh/src/index.js
+++ b/libsquoosh/src/index.js
@@ -9,7 +9,18 @@ import { autoOptimize } from './auto-optimizer.js';
 export { ImagePool, encoders, preprocessors };
 
 async function decodeFile({ file }) {
-  const buffer = await fsp.readFile(file);
+  let buffer;
+  if (ArrayBuffer.isView(file)) {
+    buffer = Buffer.from(file.buffer);
+  } else if (file instanceof ArrayBuffer) {
+    buffer = Buffer.from(file);
+  } else if (file instanceof Buffer) {
+    buffer = file;
+  } else if (typeof file === 'string') {
+    buffer = await fsp.readFile(file);
+  } else {
+    throw Error('Unexpected input type');
+  }
   const firstChunk = buffer.slice(0, 16);
   const firstChunkString = Array.from(firstChunk)
     .map((v) => String.fromCodePoint(v))