diff --git a/Cargo.lock b/Cargo.lock
index 1305cbb..9fc8be1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2,15 +2,64 @@
 # It is not intended for manual editing.
 version = 3
 
-[[package]]
-name = "anyhow"
-version = "1.0.48"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "62e1f47f7dc0422027a4e370dd4548d4d66b26782e513e98dca1e689e058a80e"
-
 [[package]]
 name = "lookaround"
 version = "0.1.0"
 dependencies = [
- "anyhow",
+ "thiserror",
 ]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ba508cc11742c0dc5c1659771673afbab7a0efab23aa17e854cbab0837ed0b43"
+dependencies = [
+ "unicode-xid",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "38bc8cc6a5f2e3655e0899c1b848643b2562f853f114bfec7be120678e3ace05"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "syn"
+version = "1.0.82"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8daf5dd0bb60cbd4137b1b587d2fc0ae729bc07cf01cd70b36a1ed5ade3b9d59"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-xid",
+]
+
+[[package]]
+name = "thiserror"
+version = "1.0.30"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "854babe52e4df1653706b98fcfc05843010039b406875930a70e4d9644e5c417"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "1.0.30"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aa32fd3f627f367fe16f893e2597ae3c05020f8bba2666a4e6ea73d377e5714b"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "unicode-xid"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ccb82d61f80a663efe1f787a51b16b5a51e3314d6ac365b08639f52387b33f3"
diff --git a/Cargo.toml b/Cargo.toml
index 1dbe791..f4105ec 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,4 +6,10 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-anyhow = "1.0.48"
+thiserror = "1.0.30"
+
+[profile.release]
+codegen-units = 1
+lto = true
+opt-level = "z"
+panic = "abort"
diff --git a/src/main.rs b/src/main.rs
index f2a6b6f..18d3cee 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,46 +2,75 @@ use std::{
 	env,
 	net::{
 		Ipv4Addr,
+		SocketAddrV4,
 		UdpSocket,
 	},
-	str::FromStr,
 };
 
-use anyhow::{
-	self,
-	Result,
-	bail,
-};
+use thiserror::Error;
 
-fn main () -> Result <()> {
+#[derive (Debug, Error)]
+enum AppError {
+	#[error (transparent)]
+	CliArgs (#[from] CliArgError),
+}
+
+#[derive (Debug, Error)]
+enum CliArgError {
+	#[error ("First argument should be a subcommand")]
+	MissingSubcommand,
+	#[error ("Unknown subcommand `{0}`")]
+	UnknownSubcommand (String),
+}
+
+struct CommonParams {
+	// Servers bind on this port, clients must send to the port
+	server_port: u16,
+	
+	// Clients and servers will all join the same multicast addr
+	multicast_addr: Ipv4Addr,
+}
+
+impl Default for CommonParams {
+	fn default () -> Self {
+		Self {
+			server_port: 9040,
+			multicast_addr: Ipv4Addr::new (225, 100, 99, 98),
+		}
+	}
+}
+
+fn main () -> Result <(), AppError> {
 	let mut args = env::args ();
 	
 	let _exe_name = args.next ();
 	
 	match args.next ().as_ref ().map (|s| &s[..]) {
-		None => bail! ("First argument must be a subcommand"),
+		None => return Err (CliArgError::MissingSubcommand.into ()),
 		Some ("client") => client ()?,
 		Some ("server") => server ()?,
-		Some (x) => bail! ("Unknown subcommand {}", x),
+		Some (x) => return Err (CliArgError::UnknownSubcommand (x.to_string ()).into ()),
 	}
 	
 	Ok (())
 }
 
-fn client () -> Result <()> {
-	let socket = UdpSocket::bind ("0.0.0.0:9041").unwrap ();
+fn client () -> Result <(), AppError> {
+	let params = CommonParams::default ();
+	let socket = UdpSocket::bind ("0.0.0.0:0").unwrap ();
 	
-	socket.join_multicast_v4 (&(Ipv4Addr::from_str ("225.100.99.98").unwrap ()), &([0u8, 0, 0, 0].into ())).unwrap ();
+	socket.join_multicast_v4 (&params.multicast_addr, &([0u8, 0, 0, 0].into ())).unwrap ();
 	
-	socket.send_to ("hi there".as_bytes (), ("225.100.99.98", 9040)).unwrap ();
+	socket.send_to ("hi there".as_bytes (), (params.multicast_addr, params.server_port)).unwrap ();
 	
 	Ok (())
 }
 
-fn server () -> Result <()> {
-	let socket = UdpSocket::bind ("0.0.0.0:9040").unwrap ();
+fn server () -> Result <(), AppError> {
+	let params = CommonParams::default ();
+	let socket = UdpSocket::bind (SocketAddrV4::new (Ipv4Addr::UNSPECIFIED, params.server_port)).unwrap ();
 	
-	socket.join_multicast_v4 (&(Ipv4Addr::from_str ("225.100.99.98").unwrap ()), &([0u8, 0, 0, 0].into ())).unwrap ();
+	socket.join_multicast_v4 (&params.multicast_addr, &([0u8, 0, 0, 0].into ())).unwrap ();
 	
 	let mut buf = vec! [0u8; 4096];
 	let (bytes_recved, remote_addr) = socket.recv_from (&mut buf).unwrap ();