diff --git a/src/11-usart/auxiliary/src/lib.rs b/src/11-usart/auxiliary/src/lib.rs
index ac126c80d..dedbe5c7d 100644
--- a/src/11-usart/auxiliary/src/lib.rs
+++ b/src/11-usart/auxiliary/src/lib.rs
@@ -9,17 +9,15 @@ pub use cortex_m::{asm::bkpt, iprint, iprintln, peripheral::ITM};
 pub use cortex_m_rt::entry;
 pub use stm32f3_discovery::stm32f3xx_hal::pac::usart1;
 
-pub mod monotimer;
-
 use stm32f3_discovery::stm32f3xx_hal::{
     prelude::*,
     serial::Serial,
     pac::{self, USART1},
+    timer::MonoTimer,
 };
-use monotimer::MonoTimer;
 
 pub fn init() -> (&'static mut usart1::RegisterBlock, MonoTimer, ITM) {
-    let cp = cortex_m::Peripherals::take().unwrap();
+    let mut cp = cortex_m::Peripherals::take().unwrap();
     let dp = pac::Peripherals::take().unwrap();
 
     let mut flash = dp.FLASH.constrain();
@@ -56,7 +54,7 @@ pub fn init() -> (&'static mut usart1::RegisterBlock, MonoTimer, ITM) {
     unsafe {
         (
             &mut *(USART1::ptr() as *mut _),
-            MonoTimer::new(cp.DWT, clocks),
+            MonoTimer::new(cp.DWT, clocks, &mut cp.DCB),
             cp.ITM,
         )
     }
diff --git a/src/11-usart/auxiliary/src/monotimer.rs b/src/11-usart/auxiliary/src/monotimer.rs
deleted file mode 100644
index be1d49fc3..000000000
--- a/src/11-usart/auxiliary/src/monotimer.rs
+++ /dev/null
@@ -1,54 +0,0 @@
-use stm32f3_discovery::stm32f3xx_hal as hal;
-
-use cortex_m::peripheral::DWT;
-use hal::{
-    rcc::Clocks,
-    time::rate::Hertz,
-};
-
-/// A monotonic nondecreasing timer. This is a resurrection of MonoTimer from
-/// the stm32f3xx-hal where it got removed after 0.6.1.
-#[derive(Clone, Copy)]
-pub struct MonoTimer {
-    frequency: Hertz,
-}
-
-// TODO: What about a refactoring to implement Clock from embedded-time?
-impl MonoTimer {
-    /// Creates a new `Monotonic` timer
-    pub fn new(mut dwt: DWT, clocks: Clocks) -> Self {
-        dwt.enable_cycle_counter();
-
-        // now the CYCCNT counter can't be stopped or resetted
-        drop(dwt);
-
-        MonoTimer {
-            frequency: clocks.hclk(),
-        }
-    }
-
-    /// Returns the frequency at which the monotonic timer is operating at
-    pub fn frequency(self) -> Hertz {
-        self.frequency
-    }
-
-    /// Returns an `Instant` corresponding to "now"
-    pub fn now(self) -> Instant {
-        Instant {
-            now: DWT::get_cycle_count(),
-        }
-    }
-}
-
-/// A measurement of a monotonically nondecreasing clock
-#[derive(Clone, Copy)]
-pub struct Instant {
-    now: u32,
-}
-
-impl Instant {
-    /// Ticks elapsed since the `Instant` was created
-    pub fn elapsed(self) -> u32 {
-        DWT::get_cycle_count().wrapping_sub(self.now)
-    }
-}