diff --git a/include/spinlock.h b/include/spinlock.h
index c8367fc0e39..6c79d356fc0 100644
--- a/include/spinlock.h
+++ b/include/spinlock.h
@@ -9,7 +9,10 @@
 #include <atomic.h>
 
 #if defined(CONFIG_ASSERT) && (CONFIG_MP_NUM_CPUS < 4)
-#include <kernel_structs.h>
+#include <misc/__assert.h>
+struct k_spinlock;
+int z_spin_lock_valid(struct k_spinlock *l);
+int z_spin_unlock_valid(struct k_spinlock *l);
 #define SPIN_VALIDATE
 #endif
 
@@ -43,11 +46,7 @@ static ALWAYS_INLINE k_spinlock_key_t k_spin_lock(struct k_spinlock *l)
 	k.key = _arch_irq_lock();
 
 #ifdef SPIN_VALIDATE
-	if (l->thread_cpu) {
-		__ASSERT((l->thread_cpu & 3) != _current_cpu->id,
-			 "Recursive spinlock");
-	}
-	l->thread_cpu = _current_cpu->id | (u32_t)_current;
+	__ASSERT(z_spin_lock_valid(l), "Recursive spinlock");
 #endif
 
 #ifdef CONFIG_SMP
@@ -61,13 +60,11 @@ static ALWAYS_INLINE k_spinlock_key_t k_spin_lock(struct k_spinlock *l)
 static ALWAYS_INLINE void k_spin_unlock(struct k_spinlock *l,
 					k_spinlock_key_t key)
 {
+	ARG_UNUSED(l);
 #ifdef SPIN_VALIDATE
-	__ASSERT(l->thread_cpu == (_current_cpu->id | (u32_t)_current),
-		 "Not my spinlock!");
-	l->thread_cpu = 0;
+	__ASSERT(z_spin_unlock_valid(l), "Not my spinlock!");
 #endif
 
-
 #ifdef CONFIG_SMP
 	/* Strictly we don't need atomic_clear() here (which is an
 	 * exchange operation that returns the old value).  We are always
@@ -86,6 +83,7 @@ static ALWAYS_INLINE void k_spin_unlock(struct k_spinlock *l,
  */
 static ALWAYS_INLINE void k_spin_release(struct k_spinlock *l)
 {
+	ARG_UNUSED(l);
 #ifdef SPIN_VALIDATE
 	__ASSERT(z_spin_unlock_valid(l), "Not my spinlock!");
 #endif
diff --git a/kernel/thread.c b/kernel/thread.c
index 50613de798a..80c391508ca 100644
--- a/kernel/thread.c
+++ b/kernel/thread.c
@@ -16,6 +16,7 @@
 #include <toolchain.h>
 #include <linker/sections.h>
 
+#include <spinlock.h>
 #include <kernel_structs.h>
 #include <misc/printk.h>
 #include <sys_clock.h>
@@ -704,3 +705,28 @@ FUNC_NORETURN void k_thread_user_mode_enter(k_thread_entry_t entry,
 	_thread_entry(entry, p1, p2, p3);
 #endif
 }
+
+/* These spinlock assertion predicates are defined here because having
+ * them in spinlock.h is a giant header ordering headache.
+ */
+#ifdef SPIN_VALIDATE
+int z_spin_lock_valid(struct k_spinlock *l)
+{
+	if (l->thread_cpu) {
+		if ((l->thread_cpu & 3) == _current_cpu->id) {
+			return 0;
+		}
+	}
+	l->thread_cpu = _current_cpu->id | (u32_t)_current;
+	return 1;
+}
+
+int z_spin_unlock_valid(struct k_spinlock *l)
+{
+	if (l->thread_cpu != (_current_cpu->id | (u32_t)_current)) {
+		return 0;
+	}
+	l->thread_cpu = 0;
+	return 1;
+}
+#endif