diff --git a/um_crypto/kuwo/src/lib.rs b/um_crypto/kuwo/src/lib.rs
index 3d64679..04dc1a7 100644
--- a/um_crypto/kuwo/src/lib.rs
+++ b/um_crypto/kuwo/src/lib.rs
@@ -1,6 +1,7 @@
 use crate::kwm_v1::CipherV1;
 use anyhow::Result;
 use byteorder::{ReadBytesExt, LE};
+use std::fmt;
 use std::io::{Cursor, Read};
 use thiserror::Error;
 use umc_qmc::QMCv2Cipher;
@@ -13,13 +14,16 @@ pub use umc_qmc::QMCv2Cipher as CipherV2;
 /// Commonly used secret key for Kuwo services.
 pub const SECRET_KEY: [u8; 8] = *b"ylzsxkwm";
 
+#[derive(Debug)]
+pub struct HeaderMagicBytes(pub [u8; 16]);
+
 #[derive(Error, Debug)]
 pub enum KuwoCryptoError {
     #[error("Invalid DES data size (expected: {0} mod 8 == 0)")]
     InvalidDesDataSize(usize),
 
-    #[error("Invalid KWM header magic bytes: {0:?}")]
-    InvalidHeaderMagic([u8; 16]),
+    #[error("Invalid KWM header magic bytes: {0}")]
+    InvalidHeaderMagic(HeaderMagicBytes),
 
     #[error("KWMv2: EKey required")]
     V2EKeyRequired,
@@ -28,6 +32,15 @@ pub enum KuwoCryptoError {
     UnsupportedVersion(usize),
 }
 
+impl fmt::Display for HeaderMagicBytes {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        for byte in self.0.iter() {
+            write!(f, "{:02x} ", byte)?;
+        }
+        Ok(())
+    }
+}
+
 pub const DATA_START_OFFSET: usize = 0x400;
 
 pub enum Cipher {