diff --git a/rp2040-hal/Cargo.toml b/rp2040-hal/Cargo.toml
index 293120799..aad5773dc 100644
--- a/rp2040-hal/Cargo.toml
+++ b/rp2040-hal/Cargo.toml
@@ -16,6 +16,7 @@ targets = ["thumbv6m-none-eabi"]
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+compiler_builtins = { version = "0.1.104", features = ["weak-intrinsics"] }
 cortex-m = "0.7.2"
 embedded-hal = { version = "0.2.5", features = ["unproven"] }
 eh1_0_alpha = { package = "embedded-hal", version = "=1.0.0-rc.1",  optional = true }
diff --git a/rp2040-hal/src/intrinsics.rs b/rp2040-hal/src/intrinsics.rs
index ca77da106..89ff1a43b 100644
--- a/rp2040-hal/src/intrinsics.rs
+++ b/rp2040-hal/src/intrinsics.rs
@@ -1,46 +1,46 @@
 /// Generate a series of aliases for an intrinsic function.
 macro_rules! intrinsics_aliases {
     (
-        extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) -> $ret:ty,
+        extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) $(-> $ret:ty)?,
     ) => {};
     (
-        unsafe extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) -> $ret:ty,
+        unsafe extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) $(-> $ret:ty)?,
     ) => {};
 
     (
-        extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) -> $ret:ty,
+        extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) $(-> $ret:ty)?,
         $alias:ident
         $($rest:ident)*
     ) => {
         #[cfg(all(target_arch = "arm", not(feature = "disable-intrinsics")))]
         mod $alias {
             #[no_mangle]
-            pub extern $abi fn $alias( $($argname: $ty),* ) -> $ret {
+            pub extern $abi fn $alias( $($argname: $ty),* ) $(-> $ret)? {
                 super::$name($($argname),*)
             }
         }
 
         intrinsics_aliases! {
-            extern $abi fn $name( $($argname: $ty),* ) -> $ret,
+            extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)?,
             $($rest)*
         }
     };
 
     (
-        unsafe extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) -> $ret:ty,
+        unsafe extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) $(-> $ret:ty)?,
         $alias:ident
         $($rest:ident)*
     ) => {
         #[cfg(all(target_arch = "arm", not(feature = "disable-intrinsics")))]
         mod $alias {
             #[no_mangle]
-            unsafe extern $abi fn $alias( $($argname: $ty),* ) -> $ret {
+            unsafe extern $abi fn $alias( $($argname: $ty),* ) $(-> $ret)? {
                 super::$name($($argname),*)
             }
         }
 
         intrinsics_aliases! {
-            unsafe extern $abi fn $name( $($argname: $ty),* ) -> $ret,
+            unsafe extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)?,
             $($rest)*
         }
     };
@@ -88,7 +88,7 @@ macro_rules! intrinsics {
     (
         #[slower_than_default]
         $(#[$($attr:tt)*])*
-        extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) -> $ret:ty {
+        extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) $(-> $ret:ty)? {
             $($body:tt)*
         }
 
@@ -97,7 +97,7 @@ macro_rules! intrinsics {
         // Not exported, but defined so the actual implementation is
         // considered used
         #[allow(dead_code)]
-        fn $name( $($argname: $ty),* ) -> $ret {
+        fn $name( $($argname: $ty),* ) $(-> $ret)? {
             $($body)*
         }
 
@@ -107,7 +107,7 @@ macro_rules! intrinsics {
     (
         #[bootrom_v2]
         $(#[$($attr:tt)*])*
-        extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) -> $ret:ty {
+        extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) $(-> $ret:ty)? {
             $($body:tt)*
         }
 
@@ -117,14 +117,14 @@ macro_rules! intrinsics {
         // considered used
         #[cfg(not(feature = "rom-v2-intrinsics"))]
         #[allow(dead_code)]
-        fn $name( $($argname: $ty),* ) -> $ret {
+        fn $name( $($argname: $ty),* ) $(-> $ret)? {
             $($body)*
         }
 
         #[cfg(feature = "rom-v2-intrinsics")]
         intrinsics! {
             $(#[$($attr)*])*
-            extern $abi fn $name( $($argname: $ty),* ) -> $ret {
+            extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)? {
                 $($body)*
             }
         }
@@ -135,7 +135,7 @@ macro_rules! intrinsics {
     (
         #[alias = $($alias:ident),*]
         $(#[$($attr:tt)*])*
-        extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) -> $ret:ty {
+        extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) $(-> $ret:ty)? {
             $($body:tt)*
         }
 
@@ -143,13 +143,13 @@ macro_rules! intrinsics {
     ) => {
         intrinsics! {
             $(#[$($attr)*])*
-            extern $abi fn $name( $($argname: $ty),* ) -> $ret {
+            extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)? {
                 $($body)*
             }
         }
 
         intrinsics_aliases! {
-            extern $abi fn $name( $($argname: $ty),* ) -> $ret,
+            extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)?,
             $($alias) *
         }
 
@@ -159,7 +159,7 @@ macro_rules! intrinsics {
     (
         #[alias = $($alias:ident),*]
         $(#[$($attr:tt)*])*
-        unsafe extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) -> $ret:ty {
+        unsafe extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) $(-> $ret:ty)? {
             $($body:tt)*
         }
 
@@ -167,13 +167,13 @@ macro_rules! intrinsics {
     ) => {
         intrinsics! {
             $(#[$($attr)*])*
-            unsafe extern $abi fn $name( $($argname: $ty),* ) -> $ret {
+            unsafe extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)? {
                 $($body)*
             }
         }
 
         intrinsics_aliases! {
-            unsafe extern $abi fn $name( $($argname: $ty),* ) -> $ret,
+            unsafe extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)?,
             $($alias) *
         }
 
@@ -183,7 +183,7 @@ macro_rules! intrinsics {
     (
         #[aeabi = $($alias:ident),*]
         $(#[$($attr:tt)*])*
-        extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) -> $ret:ty {
+        extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) $(-> $ret:ty)? {
             $($body:tt)*
         }
 
@@ -191,13 +191,13 @@ macro_rules! intrinsics {
     ) => {
         intrinsics! {
             $(#[$($attr)*])*
-            extern $abi fn $name( $($argname: $ty),* ) -> $ret {
+            extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)? {
                 $($body)*
             }
         }
 
         intrinsics_aliases! {
-            extern "aapcs" fn $name( $($argname: $ty),* ) -> $ret,
+            extern "aapcs" fn $name( $($argname: $ty),* ) $(-> $ret)?,
             $($alias) *
         }
 
@@ -206,7 +206,7 @@ macro_rules! intrinsics {
 
     (
         $(#[$($attr:tt)*])*
-        extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) -> $ret:ty {
+        extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) $(-> $ret:ty)? {
             $($body:tt)*
         }
 
@@ -214,7 +214,7 @@ macro_rules! intrinsics {
     ) => {
         #[cfg(all(target_arch = "arm", not(feature = "disable-intrinsics")))]
         $(#[$($attr)*])*
-        extern $abi fn $name( $($argname: $ty),* ) -> $ret {
+        extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)? {
             $($body)*
         }
 
@@ -222,7 +222,7 @@ macro_rules! intrinsics {
         mod $name {
             #[no_mangle]
             $(#[$($attr)*])*
-            pub extern $abi fn $name( $($argname: $ty),* ) -> $ret {
+            pub extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)? {
                 super::$name($($argname),*)
             }
         }
@@ -231,16 +231,39 @@ macro_rules! intrinsics {
         // considered used
         #[cfg(not(all(target_arch = "arm", not(feature = "disable-intrinsics"))))]
         #[allow(dead_code)]
-        fn $name( $($argname: $ty),* ) -> $ret {
+        fn $name( $($argname: $ty),* ) $(-> $ret)? {
             $($body)*
         }
 
         intrinsics!($($rest)*);
     };
 
+    // Naked functions are special: we can't generate wrappers for them since
+    // they use a custom calling convention.
     (
+        #[naked]
         $(#[$($attr:tt)*])*
-        unsafe extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) -> $ret:ty {
+        unsafe extern $abi:tt fn $name:ident( $($argname:ident:  $ty:ty),* ) $(-> $ret:ty)? {
+            $($body:tt)*
+        }
+
+        $($rest:tt)*
+    ) => (
+        mod $name {
+            #[naked]
+            $(#[$($attr)*])*
+            #[no_mangle]
+            pub unsafe extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)? {
+                $($body)*
+            }
+        }
+
+        intrinsics!($($rest)*);
+    );
+
+    (
+        $(#[$($attr:tt)*])*
+        unsafe extern $abi:tt fn $name:ident( $($argname:ident: $ty:ty),* ) $(-> $ret:ty)? {
             $($body:tt)*
         }
 
@@ -248,7 +271,7 @@ macro_rules! intrinsics {
     ) => {
         #[cfg(all(target_arch = "arm", not(feature = "disable-intrinsics")))]
         $(#[$($attr)*])*
-        unsafe extern $abi fn $name( $($argname: $ty),* ) -> $ret {
+        unsafe extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)? {
             $($body)*
         }
 
@@ -256,7 +279,7 @@ macro_rules! intrinsics {
         mod $name {
             #[no_mangle]
             $(#[$($attr)*])*
-            pub unsafe extern $abi fn $name( $($argname: $ty),* ) -> $ret {
+            pub unsafe extern $abi fn $name( $($argname: $ty),* ) $(-> $ret)? {
                 super::$name($($argname),*)
             }
         }
@@ -265,7 +288,7 @@ macro_rules! intrinsics {
         // considered used
         #[cfg(not(all(target_arch = "arm", not(feature = "disable-intrinsics"))))]
         #[allow(dead_code)]
-        unsafe fn $name( $($argname: $ty),* ) -> $ret {
+        unsafe fn $name( $($argname: $ty),* ) $(-> $ret)? {
             $($body)*
         }
 
diff --git a/rp2040-hal/src/lib.rs b/rp2040-hal/src/lib.rs
index 3f14385dc..fbb0bb894 100644
--- a/rp2040-hal/src/lib.rs
+++ b/rp2040-hal/src/lib.rs
@@ -37,6 +37,7 @@
 
 #![warn(missing_docs)]
 #![no_std]
+#![feature(naked_functions)]
 
 #[doc(hidden)]
 pub use paste;
@@ -94,6 +95,7 @@ pub use sio::Sio;
 pub use spi::Spi;
 pub use timer::Timer;
 pub use watchdog::Watchdog;
+extern crate compiler_builtins;
 // Re-export crates used in rp2040-hal's public API
 pub extern crate fugit;
 
diff --git a/rp2040-hal/src/sio.rs b/rp2040-hal/src/sio.rs
index ead75c858..c5df6ea43 100644
--- a/rp2040-hal/src/sio.rs
+++ b/rp2040-hal/src/sio.rs
@@ -278,29 +278,32 @@ core::arch::global_asm!(
 
 macro_rules! division_function {
     (
-        $name:ident $($intrinsic:ident)* ( $argty:ty ) {
+        $name:ident $intrinsic:ident $intrinsic_alias:ident ( $argty:ty ) {
             $($begin:literal),+
         }
     ) => {
         #[cfg(all(target_arch = "arm", not(feature = "disable-intrinsics")))]
-        core::arch::global_asm!(
-            // Mangle the name slightly, since this is a global symbol.
-            concat!(".global _rphal_", stringify!($name)),
-            concat!(".type _rphal_", stringify!($name), ", %function"),
-            ".align 2",
-            concat!("_rphal_", stringify!($name), ":"),
-            $(
-                concat!(".global ", stringify!($intrinsic)),
-                concat!(".type ", stringify!($intrinsic), ", %function"),
-                concat!(stringify!($intrinsic), ":"),
-            )*
-
-            "hwdivider_head",
-            $($begin),+ ,
-            "hwdivider_tail",
-        );
+        intrinsics! {
+            #[naked]
+            unsafe extern "C" fn $intrinsic() {
+                core::arch::asm!(
+                    "hwdivider_head",
+                    $($begin),+ ,
+                    "hwdivider_tail",
+                    options(noreturn)
+                    );
+            }
+            #[naked]
+            unsafe extern "C" fn $intrinsic_alias() {
+                core::arch::asm!(
+                    "hwdivider_head",
+                    $($begin),+ ,
+                    "hwdivider_tail",
+                    options(noreturn)
+                    );
+            }
+        }
 
-        #[cfg(all(target_arch = "arm", feature = "disable-intrinsics"))]
         core::arch::global_asm!(
             // Mangle the name slightly, since this is a global symbol.
             concat!(".global _rphal_", stringify!($name)),