diff --git a/agb/src/bitarray.rs b/agb/src/bitarray.rs
index f953ac1..9086e92 100644
--- a/agb/src/bitarray.rs
+++ b/agb/src/bitarray.rs
@@ -17,10 +17,10 @@ impl<const N: usize> Bitarray<N> {
     }
 
     pub fn set(&mut self, index: usize, value: bool) {
-        let value = value as u32;
+        let value = u32::from(value);
         let mask = 1 << (index % 32);
         let value_mask = value << (index % 32);
-        self.a[index / 32] = self.a[index / 32] & !mask | value_mask
+        self.a[index / 32] = self.a[index / 32] & !mask | value_mask;
     }
 
     pub fn first_zero(&self) -> Option<usize> {
diff --git a/agb/src/hash_map.rs b/agb/src/hash_map.rs
index db93655..36b0268 100644
--- a/agb/src/hash_map.rs
+++ b/agb/src/hash_map.rs
@@ -89,11 +89,13 @@ pub struct HashMap<K, V> {
 
 impl<K, V> HashMap<K, V> {
     /// Creates a `HashMap`
+    #[must_use]
     pub fn new() -> Self {
         Self::with_size(16)
     }
 
     /// Creates an empty `HashMap` with specified internal size. The size must be a power of 2
+    #[must_use]
     pub fn with_size(size: usize) -> Self {
         Self {
             nodes: NodeStorage::with_size(size),
@@ -103,6 +105,7 @@ impl<K, V> HashMap<K, V> {
 
     /// Creates an empty `HashMap` which can hold at least `capacity` elements before resizing. The actual
     /// internal size may be larger as it must be a power of 2
+    #[must_use]
     pub fn with_capacity(capacity: usize) -> Self {
         for i in 0..32 {
             let attempted_size = 1usize << i;
@@ -118,11 +121,13 @@ impl<K, V> HashMap<K, V> {
     }
 
     /// Returns the number of elements in the map
+    #[must_use]
     pub fn len(&self) -> usize {
         self.nodes.len()
     }
 
     /// Returns the number of elements the map can hold
+    #[must_use]
     pub fn capacity(&self) -> usize {
         self.nodes.capacity()
     }
@@ -149,21 +154,16 @@ impl<K, V> HashMap<K, V> {
 
     /// An iterator visiting all key-value pairs in an arbitrary order
     pub fn iter(&self) -> impl Iterator<Item = (&'_ K, &'_ V)> {
-        self.nodes
-            .nodes
-            .iter()
-            .filter_map(|node| node.key_value_ref())
+        self.nodes.nodes.iter().filter_map(Node::key_value_ref)
     }
 
     /// An iterator visiting all key-value pairs in an arbitrary order, with mutable references to the values
     pub fn iter_mut(&mut self) -> impl Iterator<Item = (&'_ K, &'_ mut V)> {
-        self.nodes
-            .nodes
-            .iter_mut()
-            .filter_map(|node| node.key_value_mut())
+        self.nodes.nodes.iter_mut().filter_map(Node::key_value_mut)
     }
 
     /// Returns `true` if the map contains no elements
+    #[must_use]
     pub fn is_empty(&self) -> bool {
         self.len() == 0
     }
@@ -1179,7 +1179,7 @@ mod test {
         fn test_entry(_gba: &mut Gba) {
             let xs = [(1, 10), (2, 20), (3, 30), (4, 40), (5, 50), (6, 60)];
 
-            let mut map: HashMap<_, _> = xs.iter().cloned().collect();
+            let mut map: HashMap<_, _> = xs.iter().copied().collect();
 
             // Existing key (insert)
             match map.entry(1) {
diff --git a/agb/src/input.rs b/agb/src/input.rs
index ce8cf2d..7c77fbd 100644
--- a/agb/src/input.rs
+++ b/agb/src/input.rs
@@ -10,8 +10,8 @@ pub enum Tri {
 
 impl From<(bool, bool)> for Tri {
     fn from(a: (bool, bool)) -> Tri {
-        let b1 = a.0 as i8;
-        let b2 = a.1 as i8;
+        let b1 = i8::from(a.0);
+        let b2 = i8::from(a.1);
         unsafe { core::mem::transmute(b2 - b1) }
     }
 }
@@ -47,6 +47,7 @@ impl Default for ButtonController {
 }
 
 impl ButtonController {
+    #[must_use]
     pub fn new() -> Self {
         let pressed = !unsafe { BUTTON_INPUT.read_volatile() };
         ButtonController {
@@ -60,6 +61,7 @@ impl ButtonController {
         self.current = !unsafe { BUTTON_INPUT.read_volatile() };
     }
 
+    #[must_use]
     pub fn x_tri(&self) -> Tri {
         let left = self.is_pressed(Button::LEFT);
         let right = self.is_pressed(Button::RIGHT);
@@ -67,6 +69,7 @@ impl ButtonController {
         (left, right).into()
     }
 
+    #[must_use]
     pub fn y_tri(&self) -> Tri {
         let up = self.is_pressed(Button::UP);
         let down = self.is_pressed(Button::DOWN);
@@ -74,25 +77,30 @@ impl ButtonController {
         (up, down).into()
     }
 
+    #[must_use]
     pub fn is_pressed(&self, keys: Button) -> bool {
-        let currently_pressed = self.current as u32;
+        let currently_pressed = u32::from(self.current);
         let keys = keys.bits();
         (currently_pressed & keys) != 0
     }
+
+    #[must_use]
     pub fn is_released(&self, keys: Button) -> bool {
         !self.is_pressed(keys)
     }
 
+    #[must_use]
     pub fn is_just_pressed(&self, keys: Button) -> bool {
-        let current = self.current as u32;
-        let previous = self.previous as u32;
+        let current = u32::from(self.current);
+        let previous = u32::from(self.previous);
         let keys = keys.bits();
         ((current & keys) != 0) && ((previous & keys) == 0)
     }
 
+    #[must_use]
     pub fn is_just_released(&self, keys: Button) -> bool {
-        let current = self.current as u32;
-        let previous = self.previous as u32;
+        let current = u32::from(self.current);
+        let previous = u32::from(self.previous);
         let keys = keys.bits();
         ((current & keys) == 0) && ((previous & keys) != 0)
     }
diff --git a/agb/src/interrupt.rs b/agb/src/interrupt.rs
index 2c80dcb..3d08d21 100644
--- a/agb/src/interrupt.rs
+++ b/agb/src/interrupt.rs
@@ -179,6 +179,7 @@ unsafe fn create_interrupt_inner(
 impl Drop for InterruptInner {
     fn drop(&mut self) {
         inner_drop(unsafe { Pin::new_unchecked(self) });
+        #[allow(clippy::needless_pass_by_value)] // needed for safety reasons
         fn inner_drop(this: Pin<&mut InterruptInner>) {
             // drop the closure allocation safely
             let _closure_box =
@@ -300,6 +301,7 @@ pub struct VBlank {}
 impl VBlank {
     /// Handles setting up everything reqired to be able to use the wait for
     /// interrupt syscall.
+    #[must_use]
     pub fn get() -> Self {
         interrupt_to_root(Interrupt::VBlank).add();
         VBlank {}
@@ -329,10 +331,10 @@ mod tests {
             let counter = Mutex::new(RefCell::new(0));
             let counter_2 = Mutex::new(RefCell::new(0));
             let _a = add_interrupt_handler(Interrupt::VBlank, |key: CriticalSection| {
-                *counter.borrow(key).borrow_mut() += 1
+                *counter.borrow(key).borrow_mut() += 1;
             });
             let _b = add_interrupt_handler(Interrupt::VBlank, |key: CriticalSection| {
-                *counter_2.borrow(key).borrow_mut() += 1
+                *counter_2.borrow(key).borrow_mut() += 1;
             });
 
             let vblank = VBlank::get();
diff --git a/agb/src/lib.rs b/agb/src/lib.rs
index 19f85d2..910c867 100644
--- a/agb/src/lib.rs
+++ b/agb/src/lib.rs
@@ -234,6 +234,7 @@ pub struct Gba {
 
 impl Gba {
     #[doc(hidden)]
+    #[must_use]
     pub unsafe fn new_in_entry() -> Self {
         GBASINGLE.take()
     }
@@ -365,7 +366,7 @@ mod test {
                 break;
             }
             vblank.wait_for_vblank();
-            counter += 1
+            counter += 1;
         }
     }
 
diff --git a/agb/src/mgba.rs b/agb/src/mgba.rs
index 02481fa..1849eed 100644
--- a/agb/src/mgba.rs
+++ b/agb/src/mgba.rs
@@ -29,7 +29,7 @@ fn is_running_in_mgba() -> bool {
 const NUMBER_OF_CYCLES: MemoryMapped<u16> = unsafe { MemoryMapped::new(0x04FF_F800) };
 
 pub fn number_of_cycles_tagged(tag: u16) {
-    NUMBER_OF_CYCLES.set(tag)
+    NUMBER_OF_CYCLES.set(tag);
 }
 
 pub struct Mgba {
@@ -37,6 +37,7 @@ pub struct Mgba {
 }
 
 impl Mgba {
+    #[must_use]
     pub fn new() -> Option<Self> {
         if is_running_in_mgba() {
             Some(Mgba { bytes_written: 0 })
diff --git a/agb/src/rng.rs b/agb/src/rng.rs
index 69d8bdf..282efad 100644
--- a/agb/src/rng.rs
+++ b/agb/src/rng.rs
@@ -15,12 +15,14 @@ impl RandomNumberGenerator {
     /// Create a new random number generator with a fixed seed
     ///
     /// Note that this seed is guaranteed to be the same between minor releases.
+    #[must_use]
     pub const fn new() -> Self {
         Self::new_with_seed([1014776995, 476057059, 3301633994, 706340607])
     }
 
     /// Produces a random number generator with the given initial state / seed.
     /// None of the values can be 0.
+    #[must_use]
     pub const fn new_with_seed(seed: [u32; 4]) -> Self {
         // this can't be in a loop because const
         assert!(seed[0] != 0, "seed must not be 0");
@@ -54,6 +56,7 @@ static GLOBAL_RNG: Mutex<RefCell<RandomNumberGenerator>> =
     Mutex::new(RefCell::new(RandomNumberGenerator::new()));
 
 /// Using a global random number generator, provides the next random number
+#[must_use]
 pub fn gen() -> i32 {
     free(|cs| GLOBAL_RNG.borrow(cs).borrow_mut().gen())
 }
diff --git a/agb/src/syscall.rs b/agb/src/syscall.rs
index da94ee6..82e2464 100644
--- a/agb/src/syscall.rs
+++ b/agb/src/syscall.rs
@@ -54,6 +54,7 @@ pub fn wait_for_vblank() {
     }
 }
 
+#[must_use]
 pub fn div(numerator: i32, denominator: i32) -> (i32, i32, i32) {
     let divide: i32;
     let modulo: i32;
@@ -71,6 +72,7 @@ pub fn div(numerator: i32, denominator: i32) -> (i32, i32, i32) {
     (divide, modulo, abs_divide)
 }
 
+#[must_use]
 pub fn sqrt(n: i32) -> i32 {
     let result: i32;
     unsafe {
@@ -86,6 +88,7 @@ pub fn sqrt(n: i32) -> i32 {
     result
 }
 
+#[must_use]
 pub fn arc_tan(n: i16) -> i16 {
     let result: i16;
     unsafe {
@@ -101,6 +104,7 @@ pub fn arc_tan(n: i16) -> i16 {
     result
 }
 
+#[must_use]
 pub fn arc_tan2(x: i16, y: i32) -> i16 {
     let result: i16;
     unsafe {
diff --git a/agb/src/timer.rs b/agb/src/timer.rs
index 6fb1a9d..5797fcd 100644
--- a/agb/src/timer.rs
+++ b/agb/src/timer.rs
@@ -21,7 +21,7 @@ pub enum Divider {
 }
 
 impl Divider {
-    fn as_bits(&self) -> u16 {
+    fn as_bits(self) -> u16 {
         use Divider::*;
 
         match self {
@@ -68,6 +68,7 @@ impl Timer {
         self
     }
 
+    #[must_use]
     pub fn value(&self) -> u16 {
         self.data_register().get()
     }
@@ -90,7 +91,7 @@ impl Timer {
     }
 
     pub fn set_interrupt(&mut self, interrupt: bool) -> &mut Self {
-        let bit = interrupt as u16;
+        let bit = u16::from(interrupt);
         self.control_register().set_bits(bit, 1, 6);
         self
     }
@@ -107,6 +108,7 @@ impl Timer {
         self.timer_number as usize
     }
 
+    #[must_use]
     pub fn interrupt(&self) -> crate::interrupt::Interrupt {
         use crate::interrupt::Interrupt;
         match self.timer_number {