diff --git a/Cargo.toml b/Cargo.toml
index 923a9e3..15943cd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,7 @@
 [package]
 name = "ico"
 version = "0.2.0"
+edition = "2021"
 authors = ["Matthew D. Steele <mdsteele@alum.mit.edu>"]
 description = "A library for encoding/decoding ICO image files"
 repository = "https://github.com/mdsteele/rust-ico"
diff --git a/examples/icotool.rs b/examples/icotool.rs
index 4ffb673..d22e077 100644
--- a/examples/icotool.rs
+++ b/examples/icotool.rs
@@ -1,6 +1,3 @@
-extern crate clap;
-extern crate ico;
-
 use clap::{App, Arg, SubCommand};
 use std::fs;
 use std::path::PathBuf;
diff --git a/src/lib.rs b/src/lib.rs
index 0f1ec04..33b5666 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -56,13 +56,9 @@
 
 #![warn(missing_docs)]
 
-extern crate byteorder;
-extern crate png;
-
 use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
 use std::collections::{BTreeSet, HashMap};
 use std::io::{self, Read, Seek, SeekFrom, Write};
-use std::{u16, u8};
 
 // ========================================================================= //