diff --git a/pw_sync_embos/interrupt_spin_lock.cc b/pw_sync_embos/interrupt_spin_lock.cc
index 2bb029c..ee2c9ed 100644
--- a/pw_sync_embos/interrupt_spin_lock.cc
+++ b/pw_sync_embos/interrupt_spin_lock.cc
@@ -20,26 +20,42 @@
 namespace pw::sync {
 
 void InterruptSpinLock::lock() {
+  // Mask interrupts.
   OS_IncDI();
+
+  // Disable task switching to ensure kernel APIs cannot switch to other tasks
+  // which could then end up deadlocking recursively on this same lock.
+  OS_SuspendAllTasks();
+
   // We can't deadlock here so crash instead.
-  PW_CHECK(!native_type_.locked.load(std::memory_order_relaxed),
+  PW_CHECK(!native_type_.locked,
            "Recursive InterruptSpinLock::lock() detected");
-  native_type_.locked.store(true, std::memory_order_relaxed);
+  native_type_.locked = true;
 }
 
 bool InterruptSpinLock::try_lock() {
+  // Mask interrupts.
   OS_IncDI();
-  if (native_type_.locked.load(std::memory_order_relaxed)) {
-    OS_DecRI();  // Already locked, restore interrupts and bail out.
+
+  // Disable task switching to ensure kernel APIs cannot switch to other tasks
+  // which could then end up deadlocking recursively on this same lock.
+  OS_SuspendAllTasks();
+
+  if (native_type_.locked) {
+    // Already locked, bail out.
+    OS_ResumeAllSuspendedTasks();  // Restore task switching.
+    OS_DecRI();                    // Restore interrupts.
     return false;
   }
-  native_type_.locked.store(true, std::memory_order_relaxed);
+
+  native_type_.locked = true;
   return true;
 }
 
 void InterruptSpinLock::unlock() {
-  native_type_.locked.store(false, std::memory_order_relaxed);
-  OS_DecRI();
+  native_type_.locked = false;
+  OS_ResumeAllSuspendedTasks();  // Restore task switching.
+  OS_DecRI();                    // Restore interrupts.
 }
 
 }  // namespace pw::sync
diff --git a/pw_sync_embos/public/pw_sync_embos/interrupt_spin_lock_inline.h b/pw_sync_embos/public/pw_sync_embos/interrupt_spin_lock_inline.h
index 0484b3c..03790cc 100644
--- a/pw_sync_embos/public/pw_sync_embos/interrupt_spin_lock_inline.h
+++ b/pw_sync_embos/public/pw_sync_embos/interrupt_spin_lock_inline.h
@@ -18,7 +18,7 @@
 namespace pw::sync {
 
 constexpr InterruptSpinLock::InterruptSpinLock()
-    : native_type_{.locked{false}} {}
+    : native_type_{.locked = false} {}
 
 inline InterruptSpinLock::native_handle_type
 InterruptSpinLock::native_handle() {
diff --git a/pw_sync_embos/public/pw_sync_embos/interrupt_spin_lock_native.h b/pw_sync_embos/public/pw_sync_embos/interrupt_spin_lock_native.h
index 3c91f64..548b67a 100644
--- a/pw_sync_embos/public/pw_sync_embos/interrupt_spin_lock_native.h
+++ b/pw_sync_embos/public/pw_sync_embos/interrupt_spin_lock_native.h
@@ -13,14 +13,12 @@
 // the License.
 #pragma once
 
-#include <atomic>
-
 #include "RTOS.h"
 
 namespace pw::sync::backend {
 
 struct NativeInterruptSpinLock {
-  std::atomic<bool> locked;  // Used to detect recursion.
+  bool locked;  // Used to detect recursion.
 };
 using NativeInterruptSpinLockHandle = NativeInterruptSpinLock&;