diff --git a/src/arm.rs b/src/arm.rs
index 0be06a4..d2544f5 100644
--- a/src/arm.rs
+++ b/src/arm.rs
@@ -1,67 +1,74 @@
-use core::intrinsics;
-
-macro_rules! defer {
-    ($($symbol:ident),+ -> $routine:ident) => {
-        $(
-            #[naked]
-            #[no_mangle]
-            pub extern "C" fn $symbol() {
-                unsafe {
-                    asm!(concat!("b ", stringify!($routine)));
-                    intrinsics::unreachable();
-                }
-            }
-        )+
-    }
+extern "C" {
+    fn memcmp(s1: *const u8, s2: *const u8, n: usize) -> i32;
+    fn memcpy(dest: *mut u8, src: *const u8, n: usize) -> *mut u8;
+    fn memmove(dest: *mut u8, src: *const u8, n: usize) -> *mut u8;
+    fn memset(dest: *mut u8, c: i32, n: usize) -> *mut u8;
 }
 
-// FIXME only `__aeabi_memcmp` should be defined like this. The `*4` and `*8` variants should be
-// defined as aliases of `__aeabi_memcmp`
-defer!(__aeabi_memcmp, __aeabi_memcmp4, __aeabi_memcmp8 -> memcmp);
+// FIXME: The `*4` and `*8` variants should be defined as aliases.
 
-// FIXME same issue as `__aeabi_memcmp*`
-defer!(__aeabi_memcpy, __aeabi_memcpy4, __aeabi_memcpy8 -> memcpy);
-
-// FIXME same issue as `__aeabi_memcmp*`
-defer!(__aeabi_memmove, __aeabi_memmove4, __aeabi_memmove8 -> memmove);
-
-macro_rules! memset {
-    ($($symbol:ident),+) => {
-        $(
-            #[naked]
-            #[no_mangle]
-            pub extern "C" fn $symbol() {
-                unsafe {
-                    asm!("mov r3, r1
-                          mov r1, r2
-                          mov r2, r3
-                          b memset");
-                    intrinsics::unreachable();
-                }
-            }
-        )+
-    }
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memcmp(s1: *const u8, s2: *const u8, n: usize) -> i32 {
+    memcmp(s1, s2, n)
+}
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memcmp4(s1: *const u8, s2: *const u8, n: usize) -> i32 {
+    memcmp(s1, s2, n)
+}
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memcmp8(s1: *const u8, s2: *const u8, n: usize) -> i32 {
+    memcmp(s1, s2, n)
 }
 
-// FIXME same issue as `__aeabi_memcmp*`
-memset!(__aeabi_memset, __aeabi_memset4, __aeabi_memset8);
-
-macro_rules! memclr {
-    ($($symbol:ident),+) => {
-        $(
-            #[naked]
-            #[no_mangle]
-            pub extern "C" fn $symbol() {
-                unsafe {
-                    asm!("mov r2, r1
-                          mov r1, #0
-                          b memset");
-                    intrinsics::unreachable();
-                }
-            }
-        )+
-    }
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memcpy(dest: *mut u8, src: *const u8, n: usize) {
+    memcpy(dest, src, n);
+}
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memcpy4(dest: *mut u8, src: *const u8, n: usize) {
+    memcpy(dest, src, n);
+}
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memcpy8(dest: *mut u8, src: *const u8, n: usize) {
+    memcpy(dest, src, n);
 }
 
-// FIXME same issue as `__aeabi_memcmp*`
-memclr!(__aeabi_memclr, __aeabi_memclr4, __aeabi_memclr8);
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memmove(dest: *mut u8, src: *const u8, n: usize) {
+    memmove(dest, src, n);
+}
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memmove4(dest: *mut u8, src: *const u8, n: usize) {
+    memmove(dest, src, n);
+}
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memmove8(dest: *mut u8, src: *const u8, n: usize) {
+    memmove(dest, src, n);
+}
+
+// Note the different argument order
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memset(dest: *mut u8, n: usize, c: i32) {
+    memset(dest, c, n);
+}
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memset4(dest: *mut u8, n: usize, c: i32) {
+    memset(dest, c, n);
+}
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memset8(dest: *mut u8, n: usize, c: i32) {
+    memset(dest, c, n);
+}
+
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memclr(dest: *mut u8, n: usize) {
+    memset(dest, 0, n);
+}
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memclr4(dest: *mut u8, n: usize) {
+    memset(dest, 0, n);
+}
+#[no_mangle]
+pub unsafe extern "aapcs" fn __aeabi_memclr8(dest: *mut u8, n: usize) {
+    memset(dest, 0, n);
+}