diff --git a/kernel/src/arch/riscv/board/virt/console.rs b/kernel/src/arch/riscv/board/virt/console.rs
index 17eb6eb..46bde94 100644
--- a/kernel/src/arch/riscv/board/virt/console.rs
+++ b/kernel/src/arch/riscv/board/virt/console.rs
@@ -23,7 +23,7 @@ impl ConsoleDevice for EarlyConsole {
         unsafe { uart.write_volatile(ch) }
     }
 
-    fn write_str(&mut self, s: &str) -> () {
+    fn write_str(&mut self, s: &str) {
         for ch in s.bytes() {
             self.write(ch);
         }
diff --git a/kernel/src/drivers/serial/sifive.rs b/kernel/src/drivers/serial/sifive.rs
index 7b43bf8..cd04828 100644
--- a/kernel/src/drivers/serial/sifive.rs
+++ b/kernel/src/drivers/serial/sifive.rs
@@ -172,7 +172,7 @@ impl ConsoleDevice for UartSifive {
         self.tx_write(n);
     }
 
-    fn write_str(&mut self, s: &str) -> () {
+    fn write_str(&mut self, s: &str) {
         for ch in s.bytes() {
             self.write(ch);
         }
diff --git a/kernel/src/drivers/serial/uart16550.rs b/kernel/src/drivers/serial/uart16550.rs
index 34c55e1..38ad12e 100644
--- a/kernel/src/drivers/serial/uart16550.rs
+++ b/kernel/src/drivers/serial/uart16550.rs
@@ -41,7 +41,7 @@ impl ConsoleDevice for Uart16550 {
         self.port.send(byte);
     }
 
-    fn write_str(&mut self, s: &str) -> () {
+    fn write_str(&mut self, s: &str) {
         self.port.write_str(s).unwrap()
     }
 }
diff --git a/kernel/src/plat/console.rs b/kernel/src/plat/console.rs
index a4e3884..031fcc8 100644
--- a/kernel/src/plat/console.rs
+++ b/kernel/src/plat/console.rs
@@ -38,7 +38,7 @@ impl ConsoleDevice for SilenceConsole {
 
     fn write(&mut self, _: u8) {}
 
-    fn write_str(&mut self, _: &str) -> () {}
+    fn write_str(&mut self, _: &str) {}
 }
 
 pub static CONSOLE: Mutex<ConsoleDriver> = Mutex::new(ConsoleDriver::SilenceConsole(SilenceConsole));