diff --git a/include/spinlock.h b/include/spinlock.h
index 5161443eca3..15ff47677b5 100644
--- a/include/spinlock.h
+++ b/include/spinlock.h
@@ -35,9 +35,10 @@ static inline void z_arch_irq_unlock(int key)
 #if (CONFIG_FLASH_SIZE == 0) || (CONFIG_FLASH_SIZE > 32)
 #if defined(CONFIG_ASSERT) && (CONFIG_MP_NUM_CPUS < 4)
 #include <misc/__assert.h>
+#include <stdbool.h>
 struct k_spinlock;
-int z_spin_lock_valid(struct k_spinlock *l);
-int z_spin_unlock_valid(struct k_spinlock *l);
+bool z_spin_lock_valid(struct k_spinlock *l);
+bool z_spin_unlock_valid(struct k_spinlock *l);
 void z_spin_lock_set_owner(struct k_spinlock *l);
 #define SPIN_VALIDATE
 #endif
diff --git a/kernel/thread.c b/kernel/thread.c
index 9cf7beddeb8..f96dbdc2f19 100644
--- a/kernel/thread.c
+++ b/kernel/thread.c
@@ -708,23 +708,23 @@ FUNC_NORETURN void k_thread_user_mode_enter(k_thread_entry_t entry,
  * them in spinlock.h is a giant header ordering headache.
  */
 #ifdef SPIN_VALIDATE
-int z_spin_lock_valid(struct k_spinlock *l)
+bool z_spin_lock_valid(struct k_spinlock *l)
 {
 	if (l->thread_cpu) {
 		if ((l->thread_cpu & 3) == _current_cpu->id) {
-			return 0;
+			return false;
 		}
 	}
-	return 1;
+	return true;
 }
 
-int z_spin_unlock_valid(struct k_spinlock *l)
+bool z_spin_unlock_valid(struct k_spinlock *l)
 {
 	if (l->thread_cpu != (_current_cpu->id | (u32_t)_current)) {
-		return 0;
+		return false;
 	}
 	l->thread_cpu = 0;
-	return 1;
+	return true;
 }
 
 void z_spin_lock_set_owner(struct k_spinlock *l)