diff --git a/Cargo.lock b/Cargo.lock
index 08c0852..634bb2f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -50,6 +50,12 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "anyhow"
+version = "1.0.80"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5ad32ce52e4161730f7098c077cd2ed6229b5804ccf99e5366be1ab72a98b4e1"
+
 [[package]]
 name = "async-attributes"
 version = "1.1.2"
@@ -327,6 +333,7 @@ dependencies = [
 name = "decoyssh"
 version = "1.0.6"
 dependencies = [
+ "anyhow",
  "async-signals",
  "async-std",
  "clap",
diff --git a/Cargo.toml b/Cargo.toml
index c305221..e449cc8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,6 +12,7 @@ include = ["src/**/*", "LICENSE", "README.md"]
 edition = "2021"
 
 [dependencies]
+anyhow = { version = "1.0.80" }
 async-std = { version = "1.12", features = ["attributes"] }
 async-signals = { version = "0.4" }
 clap = { version = "4.0", features = ["cargo", "derive", "env", "wrap_help"] }
diff --git a/src/main.rs b/src/main.rs
index 5e6229f..2321124 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -3,6 +3,7 @@ mod pool;
 
 use std::time::{Duration, Instant};
 
+use anyhow::{bail, Result};
 use async_signals::Signals;
 use async_std::io::ErrorKind;
 use async_std::net::TcpListener;
@@ -27,7 +28,7 @@ async fn process(
     pool: ConnectionPoolProxy,
     length: usize,
     delay: Duration,
-) -> Result<(SocketAddr, Duration), std::io::Error> {
+) -> Result<(SocketAddr, Duration)> {
     let addr = stream.peer_addr()?;
     let cap = length + CRLF.len();
     let now = Instant::now();
@@ -56,6 +57,7 @@ async fn process(
         }
     } else {
         stream.shutdown(Shutdown::Both)?;
+        bail!("pool is not ready");
     }
 
     pool.remove(addr).await;