diff --git a/agb-fixnum/src/lib.rs b/agb-fixnum/src/lib.rs
index 7ddc62b7..a4196b24 100644
--- a/agb-fixnum/src/lib.rs
+++ b/agb-fixnum/src/lib.rs
@@ -133,7 +133,6 @@ fixed_width_unsigned_integer_impl!(i16, i32);
 fixed_width_unsigned_integer_impl!(u16, u32);
 fixed_width_unsigned_integer_impl!(i32, i64);
 fixed_width_unsigned_integer_impl!(u32, u64);
-fixed_width_unsigned_integer_impl!(usize, u64);
 
 fixed_width_signed_integer_impl!(i16);
 fixed_width_signed_integer_impl!(i32);
diff --git a/agb/examples/mixer_basic.rs b/agb/examples/mixer_basic.rs
index 80375d77..97403e8b 100644
--- a/agb/examples/mixer_basic.rs
+++ b/agb/examples/mixer_basic.rs
@@ -26,7 +26,7 @@ fn main(mut gba: Gba) -> ! {
         {
             if let Some(channel) = mixer.channel(&channel_id) {
                 let half: Num<i16, 4> = num!(0.5);
-                let half_usize: Num<usize, 8> = num!(0.5);
+                let half_usize: Num<u32, 8> = num!(0.5);
                 match input.x_tri() {
                     Tri::Negative => channel.panning(-half),
                     Tri::Zero => channel.panning(0),
diff --git a/agb/src/sound/mixer/mod.rs b/agb/src/sound/mixer/mod.rs
index ca2a36ab..0bff6c50 100644
--- a/agb/src/sound/mixer/mod.rs
+++ b/agb/src/sound/mixer/mod.rs
@@ -224,10 +224,10 @@ impl Frequency {
 /// ```
 pub struct SoundChannel {
     data: &'static [u8],
-    pos: Num<usize, 8>,
+    pos: Num<u32, 8>,
     should_loop: bool,
 
-    playback_speed: Num<usize, 8>,
+    playback_speed: Num<u32, 8>,
     volume: Num<i16, 4>, // between 0 and 1
 
     panning: Num<i16, 4>, // between -1 and 1
@@ -336,7 +336,7 @@ impl SoundChannel {
     /// Note that this only works for mono sounds. Stereo sounds will not change
     /// how fast they play.
     #[inline(always)]
-    pub fn playback(&mut self, playback_speed: impl Into<Num<usize, 8>>) -> &mut Self {
+    pub fn playback(&mut self, playback_speed: impl Into<Num<u32, 8>>) -> &mut Self {
         self.playback_speed = playback_speed.into();
         self
     }
@@ -392,13 +392,13 @@ impl SoundChannel {
     /// Gets how far along the sound has played.
     #[inline]
     #[must_use]
-    pub fn pos(&self) -> Num<usize, 8> {
+    pub fn pos(&self) -> Num<u32, 8> {
         self.pos
     }
 
     /// Sets the playback position
     #[inline]
-    pub fn set_pos(&mut self, pos: impl Into<Num<usize, 8>>) -> &mut Self {
+    pub fn set_pos(&mut self, pos: impl Into<Num<u32, 8>>) -> &mut Self {
         self.pos = pos.into();
         self
     }
diff --git a/agb/src/sound/mixer/sw_mixer.rs b/agb/src/sound/mixer/sw_mixer.rs
index 8984f842..1962fef9 100644
--- a/agb/src/sound/mixer/sw_mixer.rs
+++ b/agb/src/sound/mixer/sw_mixer.rs
@@ -24,7 +24,7 @@ extern "C" {
     fn agb_rs__mixer_add(
         sound_data: *const u8,
         sound_buffer: *mut Num<i16, 4>,
-        playback_speed: Num<usize, 8>,
+        playback_speed: Num<u32, 8>,
         left_amount: Num<i16, 4>,
         right_amount: Num<i16, 4>,
     );
@@ -415,8 +415,8 @@ impl MixerBuffer {
                 channel.playback_speed
             };
 
-            if (channel.pos + playback_speed * self.frequency.buffer_size()).floor()
-                >= channel.data.len()
+            if (channel.pos + playback_speed * self.frequency.buffer_size() as u32).floor()
+                >= channel.data.len() as u32
             {
                 // TODO: This should probably play what's left rather than skip the last bit
                 if channel.should_loop {
@@ -431,7 +431,7 @@ impl MixerBuffer {
                 if channel.is_stereo {
                     unsafe {
                         agb_rs__mixer_add_stereo(
-                            channel.data.as_ptr().add(channel.pos.floor()),
+                            channel.data.as_ptr().add(channel.pos.floor() as usize),
                             working_buffer.as_mut_ptr(),
                             channel.volume,
                         );
@@ -442,7 +442,7 @@ impl MixerBuffer {
 
                     unsafe {
                         agb_rs__mixer_add(
-                            channel.data.as_ptr().add(channel.pos.floor()),
+                            channel.data.as_ptr().add(channel.pos.floor() as usize),
                             working_buffer.as_mut_ptr(),
                             playback_speed,
                             left_amount,
@@ -452,7 +452,7 @@ impl MixerBuffer {
                 }
             }
 
-            channel.pos += playback_speed * self.frequency.buffer_size();
+            channel.pos += playback_speed * self.frequency.buffer_size() as u32;
         }
 
         let write_buffer = free(|cs| self.state.borrow(cs).borrow_mut().active_advanced());