diff --git a/dither-image.js b/dither-image.js
index 554ae0c..2a9d5f0 100644
--- a/dither-image.js
+++ b/dither-image.js
@@ -1,5 +1,4 @@
 import {
-    readFileSync,
     writeFileSync
 } from 'fs';
 
@@ -701,7 +700,7 @@ function imageToLinearRGB(rgba) {
  * @param {string} source path to source image file
  * @returns {{width: number, height: number, lines: {palette: Array, output: Uint8Array}[]}}
  */
-async function convert(source, nbits) {
+async function convert(source) {
 
     let {
         width,