diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c
index 0804b6a..ad17644 100644
--- a/arch/alpha/kernel/smp.c
+++ b/arch/alpha/kernel/smp.c
@@ -16,6 +16,7 @@
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
+#include <linux/err.h>
 #include <linux/threads.h>
 #include <linux/smp.h>
 #include <linux/interrupt.h>