diff --git a/src/host/hardware_sync/include/hardware/sync.h b/src/host/hardware_sync/include/hardware/sync.h
index ae3865ae2..065cb3e52 100644
--- a/src/host/hardware_sync/include/hardware/sync.h
+++ b/src/host/hardware_sync/include/hardware/sync.h
@@ -109,8 +109,6 @@ extern "C" {
 
 void __sev();
 
-void __wev();
-
 void __wfi();
 
 void __wfe();
diff --git a/src/host/hardware_sync/sync_core0_only.c b/src/host/hardware_sync/sync_core0_only.c
index 70964c4b0..2578f0413 100644
--- a/src/host/hardware_sync/sync_core0_only.c
+++ b/src/host/hardware_sync/sync_core0_only.c
@@ -93,23 +93,44 @@ void PICO_WEAK_FUNCTION_IMPL_NAME(spin_unlock)(spin_lock_t *lock, uint32_t saved
     spin_unlock_unsafe(lock);
 }
 
-PICO_WEAK_FUNCTION_DEF(__sev)
+// These are defined on ARM hosts, but don't do what we want for the host
+// since this is a simulated build.
+
+#if PICO_C_COMPILER_IS_GNU || !__has_builtin(__sev)
+#define __sev_c __sev
+#else
+#pragma redefine_extname __sev_c __sev
+#endif
+
+#if PICO_C_COMPILER_IS_GNU || !__has_builtin(__wfi)
+#define __wfi_c __wfi
+#else
+#pragma redefine_extname __wfi_c __wfi
+#endif
+
+#if PICO_C_COMPILER_IS_GNU || !__has_builtin(__wfe)
+#define __wfe_c __wfe
+#else
+#pragma redefine_extname __wfe_c __wfe
+#endif
+
+PICO_WEAK_FUNCTION_DEF(__sev_c)
 
 volatile bool event_fired;
 
-void PICO_WEAK_FUNCTION_IMPL_NAME(__sev)() {
+void PICO_WEAK_FUNCTION_IMPL_NAME(__sev_c)() {
     event_fired = true;
 }
 
-PICO_WEAK_FUNCTION_DEF(__wfi)
+PICO_WEAK_FUNCTION_DEF(__wfi_c)
 
-void PICO_WEAK_FUNCTION_IMPL_NAME(__wfi)() {
+void PICO_WEAK_FUNCTION_IMPL_NAME(__wfi_c)() {
     panic("Can't wait on irq for host core0 only implementation");
 }
 
-PICO_WEAK_FUNCTION_DEF(__wfe)
+PICO_WEAK_FUNCTION_DEF(__wfe_c)
 
-void PICO_WEAK_FUNCTION_IMPL_NAME(__wfe)() {
+void PICO_WEAK_FUNCTION_IMPL_NAME(__wfe_c)() {
     while (!event_fired) tight_loop_contents();
 }
 
@@ -146,4 +167,4 @@ int PICO_WEAK_FUNCTION_IMPL_NAME(spin_lock_claim_unused)(bool required) {
 PICO_WEAK_FUNCTION_DEF(spin_lock_num)
 uint PICO_WEAK_FUNCTION_IMPL_NAME(spin_lock_num)(spin_lock_t *lock) {
     return 0;
-}
\ No newline at end of file
+}
diff --git a/src/rp2_common/hardware_exception/exception.c b/src/rp2_common/hardware_exception/exception.c
index 52a5b64c0..7cb7cc464 100644
--- a/src/rp2_common/hardware_exception/exception.c
+++ b/src/rp2_common/hardware_exception/exception.c
@@ -35,7 +35,7 @@ static inline exception_handler_t *get_exception_table(void) {
 static void set_raw_exception_handler_and_restore_interrupts(enum exception_number num, exception_handler_t handler, uint32_t save) {
     // update vtable (vtable_handler may be same or updated depending on cases, but we do it anyway for compactness)
     get_exception_table()[num] = handler;
-    __dmb();
+    __DMB();
     restore_interrupts_from_disabled(save);
 }
 #endif
@@ -108,4 +108,4 @@ uint exception_get_priority(uint num) {
     }
     return PICO_LOWEST_EXCEPTION_PRIORITY;
 }
-#endif
\ No newline at end of file
+#endif
diff --git a/src/rp2_common/hardware_irq/irq.c b/src/rp2_common/hardware_irq/irq.c
index fdcbb00fb..4260f8d9b 100644
--- a/src/rp2_common/hardware_irq/irq.c
+++ b/src/rp2_common/hardware_irq/irq.c
@@ -132,7 +132,7 @@ void irq_set_pending(uint num) {
 static void set_raw_irq_handler_and_unlock(uint num, irq_handler_t handler, uint32_t save) {
     // update vtable (vtable_handler may be same or updated depending on cases, but we do it anyway for compactness)
     get_vtable()[VTABLE_FIRST_IRQ + num] = handler;
-    __dmb();
+    __DMB();
     spin_unlock(spin_lock_instance(PICO_SPINLOCK_ID_IRQ), save);
 }
 #endif
@@ -498,7 +498,7 @@ void irq_remove_handler(uint num, irq_handler_t handler) {
             // Note that a irq handler chain is local to our own core, so we don't need to worry about the other core
             bool was_enabled = irq_is_enabled(num);
             irq_set_enabled(num, false);
-            __dmb();
+            __DMB();
 
             // It is possible we are being called while an IRQ for this chain is already in progress.
             // The issue we have here is that we must not free a slot that is currently being executed, because
diff --git a/src/rp2_common/hardware_sync/include/hardware/sync.h b/src/rp2_common/hardware_sync/include/hardware/sync.h
index 69b3e69a0..49aa30972 100644
--- a/src/rp2_common/hardware_sync/include/hardware/sync.h
+++ b/src/rp2_common/hardware_sync/include/hardware/sync.h
@@ -62,12 +62,19 @@ extern "C" {
 #endif
 #endif
 
+#if (__ARM_ACLE >= 200)
+// If the compiler offers arm_acle.h, don't try to re-define symbols from
+// the header.
+#include <arm_acle.h>
+#else
+
 /*! \brief Insert a NOP instruction in to the code path.
  *  \ingroup hardware_sync
  *
  * NOP does nothing for one cycle. On RP2350 Arm binaries this is forced to be
  * a 32-bit instruction to avoid dual-issue of NOPs.
  */
+#if !__has_builtin(__nop)
 __force_inline static void __nop(void) {
 #if !__ARM_ARCH_6M__
 #ifdef __riscv
@@ -79,6 +86,7 @@ __force_inline static void __nop(void) {
     __asm volatile ("nop");
 #endif
 }
+#endif
 
 
 /*! \brief Insert a SEV instruction in to the code path.
@@ -129,13 +137,15 @@ __force_inline static void __wfi(void) {
  * The DMB (data memory barrier) acts as a memory barrier, all memory accesses prior to this
  * instruction will be observed before any explicit access after the instruction.
  */
-__force_inline static void __dmb(void) {
+#if !__has_builtin(__dmb)
+__force_inline static void __dmb(unsigned int) {
 #ifdef __riscv
     __asm volatile ("fence rw, rw" : : : "memory");
 #else
     pico_default_asm_volatile ("dmb" : : : "memory");
 #endif
 }
+#endif
 
 /*! \brief Insert a DSB instruction in to the code path.
  *  \ingroup hardware_sync
@@ -144,13 +154,15 @@ __force_inline static void __dmb(void) {
  * memory barrier (DMB). The DSB operation completes when all explicit memory
  * accesses before this instruction complete.
  */
-__force_inline static void __dsb(void) {
+#if !__has_builtin(__dsb)
+__force_inline static void __dsb(unsigned int) {
 #ifdef __riscv
     __asm volatile ("fence rw, rw" : : : "memory");
 #else
     pico_default_asm_volatile ("dsb" : : : "memory");
 #endif
 }
+#endif
 
 /*! \brief Insert a ISB instruction in to the code path.
  *  \ingroup hardware_sync
@@ -159,13 +171,29 @@ __force_inline static void __dsb(void) {
  * so that all instructions following the ISB are fetched from cache or memory again, after
  * the ISB instruction has been completed.
  */
-__force_inline static void __isb(void) {
+#if !__has_builtin(__isb)
+__force_inline static void __isb(unsigned int) {
 #ifdef __riscv
     __asm volatile ("fence.i" : : : "memory");
 #else
     pico_default_asm_volatile("isb" ::: "memory");
 #endif
 }
+#endif
+
+#endif /* (__ARM_ACLE >= 200) */
+
+#ifndef __DMB
+#define __DMB() __dmb(0xf)
+#endif
+
+#ifndef __DSB
+#define __DSB() __dsb(0xf)
+#endif
+
+#ifndef __ISB
+#define __ISB() __isb(0xf)
+#endif
 
 /*! \brief Acquire a memory fence
  *  \ingroup hardware_sync
@@ -174,7 +202,7 @@ __force_inline static void __mem_fence_acquire(void) {
     // the original code below makes it hard for us to be included from C++ via a header
     // which itself is in an extern "C", so just use __dmb instead, which is what
     // is required on Cortex M0+
-    __dmb();
+    __DMB();
 //#ifndef __cplusplus
 //    atomic_thread_fence(memory_order_acquire);
 //#else
@@ -190,7 +218,7 @@ __force_inline static void __mem_fence_release(void) {
     // the original code below makes it hard for us to be included from C++ via a header
     // which itself is in an extern "C", so just use __dmb instead, which is what
     // is required on Cortex M0+
-    __dmb();
+    __DMB();
 //#ifndef __cplusplus
 //    atomic_thread_fence(memory_order_release);
 //#else
diff --git a/src/rp2_common/hardware_xip_cache/xip_cache.c b/src/rp2_common/hardware_xip_cache/xip_cache.c
index 5a78ec0f4..48083fdc9 100644
--- a/src/rp2_common/hardware_xip_cache/xip_cache.c
+++ b/src/rp2_common/hardware_xip_cache/xip_cache.c
@@ -18,7 +18,7 @@ typedef enum {
 #endif
 
 // Used to ensure subsequent accesses observe the new state of the maintained cache lines
-#define __post_maintenance_barrier() do {__dsb(); __isb();} while (0)
+#define __post_maintenance_barrier() do {__DSB(); __ISB();} while (0)
 
 // All functions in this file are marked non-flash, even though they themselves may be executed
 // safely from flash, because they are likely to be called during a flash programming operation