diff --git a/src/i2c.rs b/src/i2c.rs
index 55fa879..7d5fa80 100644
--- a/src/i2c.rs
+++ b/src/i2c.rs
@@ -203,7 +203,7 @@ impl<I2C, SCLPIN, SDAPIN> I2c<I2C, SCLPIN, SDAPIN>
 where
     I2C: Deref<Target = I2cRegisterBlock>,
 {
-    fn i2c_init(self: Self, speed: KiloHertz) -> Self {
+    fn i2c_init(self, speed: KiloHertz) -> Self {
         use core::cmp;
 
         // Make sure the I2C unit is disabled so we can configure it
diff --git a/src/rcc.rs b/src/rcc.rs
index ae79f5e..32c51ec 100644
--- a/src/rcc.rs
+++ b/src/rcc.rs
@@ -559,17 +559,15 @@ impl CFGR {
                 feature = "stm32f091",
                 feature = "stm32f098",
             ))]
-            match self.crs {
-                Some(crs) => {
-                    self.rcc.apb1enr.modify(|_, w| w.crsen().set_bit());
-
-                    // Initialize clock recovery
-                    // Set autotrim enabled.
-                    crs.cr.modify(|_, w| w.autotrimen().set_bit());
-                    // Enable CR
-                    crs.cr.modify(|_, w| w.cen().set_bit());
-                }
-                _ => {}
+
+            if let Some(crs) = self.crs {
+                self.rcc.apb1enr.modify(|_, w| w.crsen().set_bit());
+
+                // Initialize clock recovery
+                // Set autotrim enabled.
+                crs.cr.modify(|_, w| w.autotrimen().set_bit());
+                // Enable CR
+                crs.cr.modify(|_, w| w.cen().set_bit());
             }
 
             // use HSI as source
diff --git a/src/serial.rs b/src/serial.rs
index 5fe0541..c06f4e7 100644
--- a/src/serial.rs
+++ b/src/serial.rs
@@ -72,6 +72,7 @@ use core::marker::PhantomData;
 
 /// Serial error
 #[derive(Debug)]
+#[non_exhaustive]
 pub enum Error {
     /// Framing error
     Framing,
@@ -81,8 +82,6 @@ pub enum Error {
     Overrun,
     /// Parity check error
     Parity,
-    #[doc(hidden)]
-    _Extensible,
 }
 
 /// Interrupt event
diff --git a/src/spi.rs b/src/spi.rs
index 8d31fd8..8a2fd8c 100644
--- a/src/spi.rs
+++ b/src/spi.rs
@@ -75,6 +75,7 @@ pub struct SixteenBit;
 
 /// SPI error
 #[derive(Debug)]
+#[non_exhaustive]
 pub enum Error {
     /// Overrun occurred
     Overrun,
@@ -82,8 +83,6 @@ pub enum Error {
     ModeFault,
     /// CRC error
     Crc,
-    #[doc(hidden)]
-    _Extensible,
 }
 
 /// SPI abstraction
@@ -445,7 +444,7 @@ where
 
         for word in words.iter_mut() {
             nb::block!(self.check_send())?;
-            self.send_u8(word.clone());
+            self.send_u8(*word);
             nb::block!(self.check_read())?;
             *word = self.read_u8();
         }
@@ -522,7 +521,7 @@ where
 
         for word in words {
             nb::block!(self.check_send())?;
-            self.send_u16(word.clone());
+            self.send_u16(*word);
         }
 
         // Do one last status register check before continuing