diff --git a/kernel/Cargo.lock b/kernel/Cargo.lock
index a4eacbc..7ca71d5 100644
--- a/kernel/Cargo.lock
+++ b/kernel/Cargo.lock
@@ -393,9 +393,9 @@ dependencies = [
  "riscv 0.5.0 (git+https://github.com/rcore-os/riscv)",
  "smoltcp 0.5.0 (git+https://github.com/rcore-os/smoltcp)",
  "spin 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "uart_16550 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "uart_16550 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "volatile 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "x86_64 0.5.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "x86_64 0.5.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "xmas-elf 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -555,11 +555,11 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "uart_16550"
-version = "0.1.0"
+version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "x86_64 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)",
+ "x86_64 0.5.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -615,18 +615,6 @@ dependencies = [
  "raw-cpuid 6.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "x86_64"
-version = "0.2.14"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "bit_field 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "os_bootinfo 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "usize_conversions 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "ux 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
 [[package]]
 name = "x86_64"
 version = "0.3.6"
@@ -642,7 +630,7 @@ dependencies = [
 
 [[package]]
 name = "x86_64"
-version = "0.5.3"
+version = "0.5.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "array-init 0.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -734,7 +722,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum tempdir 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)" = "15f2b5fb00ccdf689e0149d1b1b3c03fead81c2b37735d812fa8bddbbf41b6d8"
 "checksum tock-registers 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3a385d94f3f62e60445a0adb9ff8d9621faa272234530d4c0f848ec98f88e316"
 "checksum typenum 1.10.0 (registry+https://github.com/rust-lang/crates.io-index)" = "612d636f949607bdf9b123b4a6f6d966dedf3ff669f7f045890d3a4a73948169"
-"checksum uart_16550 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "269f953d8de3226f7c065c589c7b4a3e83d10a419c7c3b5e2e0f197e6acc966e"
+"checksum uart_16550 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5b9392f60931fe3bf8f24e0a15ee4f51528770f1d64c48768ab66571334d95b0"
 "checksum unicode-width 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "882386231c45df4700b275c7ff55b6f3698780a650026380e72dabe76fa46526"
 "checksum unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "fc72304796d0818e357ead4e000d19c9c174ab23dc11093ac919054d20a6a7fc"
 "checksum usize_conversions 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f70329e2cbe45d6c97a5112daad40c34cd9a4e18edb5a2a18fefeb584d8d25e5"
@@ -744,8 +732,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum winapi-i686-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
 "checksum winapi-x86_64-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
 "checksum x86 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)" = "841e1ca5a87068718a2a26f2473c6f93cf3b8119f9778fa0ae4b39b664d9e66a"
-"checksum x86_64 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)" = "2bd647af1614659e1febec1d681231aea4ebda4818bf55a578aff02f3e4db4b4"
 "checksum x86_64 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "f9258d7e2dd25008d69e8c9e9ee37865887a5e1e3d06a62f1cb3f6c209e6f177"
-"checksum x86_64 0.5.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8f7e92e985f4052118fd69f2b366c67e91288c0f01f4ae52610dce236425dfa0"
+"checksum x86_64 0.5.4 (registry+https://github.com/rust-lang/crates.io-index)" = "1d0a8201f52d2c7b373c7243dcdfb27c0dd5012f221ef6a126f507ee82005204"
 "checksum xmas-elf 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)" = "22678df5df766e8d1e5d609da69f0c3132d794edf6ab5e75e7abcd2270d4cf58"
 "checksum zero 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "5f1bc8a6b2005884962297587045002d8cfb8dcec9db332f4ca216ddc5de82c5"
diff --git a/kernel/Cargo.toml b/kernel/Cargo.toml
index a0de505..a226293 100644
--- a/kernel/Cargo.toml
+++ b/kernel/Cargo.toml
@@ -70,7 +70,7 @@ bootloader = { git = "https://github.com/rcore-os/bootloader" }
 apic = { git = "https://github.com/rcore-os/apic-rs" }
 x86_64 = "0.5"
 raw-cpuid = "6.0"
-uart_16550 = "0.1"
+uart_16550 = "0.2"
 pc-keyboard = "0.5"
 
 [target.'cfg(any(target_arch = "riscv32", target_arch = "riscv64"))'.dependencies]
diff --git a/kernel/src/arch/x86_64/driver/serial.rs b/kernel/src/arch/x86_64/driver/serial.rs
index ce84af5..68655e2 100644
--- a/kernel/src/arch/x86_64/driver/serial.rs
+++ b/kernel/src/arch/x86_64/driver/serial.rs
@@ -1,5 +1,3 @@
-// Copy from Redox
-
 use once::*;
 use spin::Mutex;
 use uart_16550::SerialPort;
@@ -7,8 +5,8 @@ use x86_64::instructions::port::Port;
 
 use crate::arch::interrupt::{consts, enable_irq};
 
-pub static COM1: Mutex<SerialPort> = Mutex::new(SerialPort::new(0x3F8));
-pub static COM2: Mutex<SerialPort> = Mutex::new(SerialPort::new(0x2F8));
+pub static COM1: Mutex<SerialPort> = Mutex::new(unsafe { SerialPort::new(0x3F8) });
+pub static COM2: Mutex<SerialPort> = Mutex::new(unsafe { SerialPort::new(0x2F8) });
 
 pub fn init() {
     assert_has_not_been_called!("serial::init must be called only once");
@@ -27,7 +25,6 @@ impl SerialRead for SerialPort {
     fn receive(&mut self) -> u8 {
         unsafe {
             let ports = self as *mut _ as *mut [Port<u8>; 6];
-            let _line_sts = &(*ports)[5];
             let data = &(*ports)[0];
             data.read()
         }
diff --git a/kernel/src/arch/x86_64/driver/vga.rs b/kernel/src/arch/x86_64/driver/vga.rs
index 7055661..41f6b9f 100644
--- a/kernel/src/arch/x86_64/driver/vga.rs
+++ b/kernel/src/arch/x86_64/driver/vga.rs
@@ -206,11 +206,11 @@ impl AsciiConsole for VgaWriter {
             CSI::CursorMove(dx, dy) => {
                 let x = (self.pos.row.0 as i8 + dx).max(0) as u8;
                 let y = (self.pos.col.0 as i8 + dy).max(0) as u8;
-                self.set_pos(Position::new(Row(x), Col(y)));
+                self.set_pos(Position::new(Row(x), Col(y))).unwrap();
             }
             CSI::CursorMoveLine(dx) => {
                 let x = (self.pos.row.0 as i8 + dx).max(0) as u8;
-                self.set_pos(Position::new(Row(x), Col(0)));
+                self.set_pos(Position::new(Row(x), Col(0))).unwrap();
             }
             _ => {}
         }
diff --git a/kernel/src/lib.rs b/kernel/src/lib.rs
index 779b75f..fa5f0a6 100644
--- a/kernel/src/lib.rs
+++ b/kernel/src/lib.rs
@@ -6,6 +6,7 @@
 #![feature(optin_builtin_traits)]
 #![feature(panic_info_message)]
 #![feature(global_asm)]
+#![deny(unused_must_use)]
 #![no_std]
 
 // just keep it ...