diff --git a/src/eth/mod.rs b/src/eth/mod.rs
index 910da875..049dfd50 100644
--- a/src/eth/mod.rs
+++ b/src/eth/mod.rs
@@ -3,7 +3,7 @@ use crate::regs::*;
 mod regs;
 
 pub struct Eth {
-    regs: &'static regs::RegisterBlock,
+    regs: &'static mut regs::RegisterBlock,
 }
 
 impl Eth {
diff --git a/src/regs.rs b/src/regs.rs
index 182b2d45..32b106f5 100644
--- a/src/regs.rs
+++ b/src/regs.rs
@@ -18,11 +18,11 @@ pub trait RegisterW {
     type W;
 
     fn zeroed() -> Self::W;
-    fn write(&self, w: Self::W);
+    fn write(&mut self, w: Self::W);
 }
 /// A modifiable register
 pub trait RegisterRW: RegisterR + RegisterW {
-    fn modify<F: FnOnce(<Self as RegisterR>::R, <Self as RegisterW>::W) -> <Self as RegisterW>::W>(&self, f: F);
+    fn modify<F: FnOnce(<Self as RegisterR>::R, <Self as RegisterW>::W) -> <Self as RegisterW>::W>(&mut self, f: F);
 }
 
 #[doc(hidden)]
@@ -69,7 +69,7 @@ macro_rules! register_w {
                 $mod_name::Write { inner: 0 }
             }
 
-            fn write(&self, w: Self::W) {
+            fn write(&mut self, w: Self::W) {
                 unsafe {
                     self.inner.write(w.inner);
                 }
@@ -82,7 +82,7 @@ macro_rules! register_w {
 macro_rules! register_rw {
     ($mod_name: ident, $struct_name: ident) => (
         impl crate::regs::RegisterRW for $struct_name {
-            fn modify<F: FnOnce(Self::R, Self::W) -> Self::W>(&self, f: F) {
+            fn modify<F: FnOnce(Self::R, Self::W) -> Self::W>(&mut self, f: F) {
                 unsafe {
                     self.inner.modify(|inner| {
                         f($mod_name::Read { inner }, $mod_name::Write { inner })
diff --git a/src/slcr.rs b/src/slcr.rs
index 4d814c12..0a13fdd6 100644
--- a/src/slcr.rs
+++ b/src/slcr.rs
@@ -197,10 +197,10 @@ pub struct RegisterBlock {
 register_at!(RegisterBlock, 0xF8000000, new);
 
 impl RegisterBlock {
-    pub fn unlocked<F: FnMut(&Self) -> R, R>(mut f: F) -> R {
-        let self_ = Self::new();
+    pub fn unlocked<F: FnMut(&mut Self) -> R, R>(mut f: F) -> R {
+        let mut self_ = Self::new();
         self_.slcr_unlock.unlock();
-        let r = f(&self_);
+        let r = f(&mut self_);
         self_.slcr_lock.lock();
         r
     }
@@ -209,7 +209,7 @@ impl RegisterBlock {
 register!(slcr_lock, SlcrLock, WO, u32);
 register_bits!(slcr_lock, lock_key, u16, 0, 15);
 impl SlcrLock {
-    pub fn lock(&self) {
+    pub fn lock(&mut self) {
         self.write(
             Self::zeroed()
                 .lock_key(0x767B)
@@ -220,7 +220,7 @@ impl SlcrLock {
 register!(slcr_unlock, SlcrUnlock, WO, u32);
 register_bits!(slcr_unlock, unlock_key, u16, 0, 15);
 impl SlcrUnlock {
-    pub fn unlock(&self) {
+    pub fn unlock(&mut self) {
         self.write(
             Self::zeroed()
                 .unlock_key(0xDF0D)
@@ -232,11 +232,11 @@ register!(aper_clk_ctrl, AperClkCtrl, RW, u32);
 register_bit!(aper_clk_ctrl, uart1_cpu_1xclkact, 21);
 register_bit!(aper_clk_ctrl, uart0_cpu_1xclkact, 20);
 impl AperClkCtrl {
-    pub fn enable_uart0(&self) {
+    pub fn enable_uart0(&mut self) {
         self.modify(|_, w| w.uart0_cpu_1xclkact(true));
     }
 
-    pub fn enable_uart1(&self) {
+    pub fn enable_uart1(&mut self) {
         self.modify(|_, w| w.uart1_cpu_1xclkact(true));
     }
 }
@@ -249,7 +249,7 @@ register_bits!(uart_clk_ctrl, divisor, u8, 8, 13);
 register_bits!(uart_clk_ctrl, srcsel, u8, 4, 5);
 register_at!(UartClkCtrl, 0xF8000154, new);
 impl UartClkCtrl {
-    pub fn enable_uart0(&self) {
+    pub fn enable_uart0(&mut self) {
         self.modify(|_, w| {
             // a. Clock divisor, slcr.UART_CLK_CTRL[DIVISOR] = 0x14.
             // b. Select the IO PLL, slcr.UART_CLK_CTRL[SRCSEL] = 0.
@@ -260,7 +260,7 @@ impl UartClkCtrl {
         })
     }
 
-    pub fn enable_uart1(&self) {
+    pub fn enable_uart1(&mut self) {
         self.modify(|_, w| {
             // a. Clock divisor, slcr.UART_CLK_CTRL[DIVISOR] = 0x14.
             // b. Select the IO PLL, slcr.UART_CLK_CTRL[SRCSEL] = 0.
@@ -279,7 +279,7 @@ register_bit!(uart_rst_ctrl, uart0_cpu1x_rst, 1);
 register_bit!(uart_rst_ctrl, uart1_cpu1x_rst, 0);
 register_at!(UartRstCtrl, 0xF8000228, new);
 impl UartRstCtrl {
-    pub fn reset_uart0(&self) {
+    pub fn reset_uart0(&mut self) {
         self.modify(|_, w|
             w.uart0_ref_rst(true)
              .uart0_cpu1x_rst(true)
@@ -290,7 +290,7 @@ impl UartRstCtrl {
         );
     }
 
-    pub fn reset_uart1(&self) {
+    pub fn reset_uart1(&mut self) {
         self.modify(|_, w|
             w.uart1_ref_rst(true)
              .uart1_cpu1x_rst(true)
diff --git a/src/uart/baud_rate_gen.rs b/src/uart/baud_rate_gen.rs
index 9904658e..38914ed0 100644
--- a/src/uart/baud_rate_gen.rs
+++ b/src/uart/baud_rate_gen.rs
@@ -10,7 +10,7 @@ fn div_round_closest(q: u32, d: u32) -> u32 {
 }
 
 /// Algorithm as in the Linux 5.1 driver
-pub fn configure(regs: &RegisterBlock, mut clk: u32, baud: u32) {
+pub fn configure(regs: &mut RegisterBlock, mut clk: u32, baud: u32) {
     if regs.mode.read().clks() {
         clk /= 8;
     }
diff --git a/src/uart/mod.rs b/src/uart/mod.rs
index 64206f54..6356d023 100644
--- a/src/uart/mod.rs
+++ b/src/uart/mod.rs
@@ -42,14 +42,14 @@ impl Uart {
             slcr.aper_clk_ctrl.enable_uart1();
             slcr.uart_clk_ctrl.enable_uart1();
         });
-        let self_ = Uart {
+        let mut self_ = Uart {
             regs: regs::RegisterBlock::uart1(),
         };
         self_.configure(baudrate);
         self_
     }
 
-    pub fn write_byte(&self, value: u8) {
+    pub fn write_byte(&mut self, value: u8) {
         while self.tx_fifo_full() {}
 
         self.regs.tx_rx_fifo.write(
@@ -58,7 +58,7 @@ impl Uart {
         );
     }
 
-    pub fn configure(&self, baudrate: u32) {
+    pub fn configure(&mut self, baudrate: u32) {
         // Configure UART character frame
         // * Disable clock-divider
         // * 8-bit
@@ -76,7 +76,7 @@ impl Uart {
         self.disable_rx();
         self.disable_tx();
 
-        baud_rate_gen::configure(&self.regs, UART_REF_CLK, baudrate);
+        baud_rate_gen::configure(self.regs, UART_REF_CLK, baudrate);
 
         // Enable controller
         self.reset_rx();
@@ -89,41 +89,41 @@ impl Uart {
         self.set_break(false, true);
     }
 
-    fn disable_rx(&self) {
+    fn disable_rx(&mut self) {
         self.regs.control.modify(|_, w| {
             w.rxen(false)
              .rxdis(true)
         })
     }
 
-    fn disable_tx(&self) {
+    fn disable_tx(&mut self) {
         self.regs.control.modify(|_, w| {
             w.txen(false)
              .txdis(true)
         })
     }
 
-    fn enable_rx(&self) {
+    fn enable_rx(&mut self) {
         self.regs.control.modify(|_, w| {
             w.rxen(true)
              .rxdis(false)
         })
     }
 
-    fn enable_tx(&self) {
+    fn enable_tx(&mut self) {
         self.regs.control.modify(|_, w| {
             w.txen(true)
              .txdis(false)
         })
     }
 
-    fn reset_rx(&self) {
+    fn reset_rx(&mut self) {
         self.regs.control.modify(|_, w| {
             w.rxrst(true)
         })
     }
 
-    fn reset_tx(&self) {
+    fn reset_tx(&mut self) {
         self.regs.control.modify(|_, w| {
             w.txrst(true)
         })
@@ -138,7 +138,7 @@ impl Uart {
         }
     }
 
-    fn set_break(&self, startbrk: bool, stopbrk: bool) {
+    fn set_break(&mut self, startbrk: bool, stopbrk: bool) {
         self.regs.control.modify(|_, w| {
             w.sttbrk(startbrk)
              .stpbrk(stopbrk)
@@ -146,7 +146,7 @@ impl Uart {
     }
 
     // 0 disables
-    fn set_rx_timeout(&self, enable: bool) {
+    fn set_rx_timeout(&mut self, enable: bool) {
         self.regs.control.modify(|_, w| {
             w.rstto(enable)
         })