diff --git a/include/zephyr/kernel.h b/include/zephyr/kernel.h
index f20219cf0f0..be1e7d65b7e 100644
--- a/include/zephyr/kernel.h
+++ b/include/zephyr/kernel.h
@@ -5931,10 +5931,6 @@ static inline void k_cpu_atomic_idle(unsigned int key)
 /**
  * @internal
  */
-extern void z_init_thread_base(struct _thread_base *thread_base,
-			      int priority, uint32_t initial_state,
-			      unsigned int options);
-
 #ifdef CONFIG_MULTITHREADING
 /**
  * @internal
diff --git a/kernel/include/kernel_internal.h b/kernel/include/kernel_internal.h
index cd5b1220aae..3c379559f72 100644
--- a/kernel/include/kernel_internal.h
+++ b/kernel/include/kernel_internal.h
@@ -24,8 +24,11 @@
 extern "C" {
 #endif
 
-/* Early boot functions */
+/* Initialize a thread */
+void z_init_thread_base(struct _thread_base *thread_base, int priority,
+			uint32_t initial_state, unsigned int options);
 
+/* Early boot functions */
 void z_early_memset(void *dst, int c, size_t n);
 void z_early_memcpy(void *dst, const void *src, size_t n);