diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index 9d5f7b0..d6c5fc0 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -15,6 +15,8 @@
 
 #include "smpboot.h"
 
+#ifdef CONFIG_SMP
+
 #ifdef CONFIG_GENERIC_SMP_IDLE_THREAD
 /*
  * For the hotplug case we keep the task structs around and reuse
@@ -72,6 +74,8 @@
 }
 #endif
 
+#endif /* #ifdef CONFIG_SMP */
+
 static LIST_HEAD(hotplug_threads);
 static DEFINE_MUTEX(smpboot_threads_lock);