diff --git a/arch/openrisc/kernel/head.S b/arch/openrisc/kernel/head.S
index b357e7f79aca..1d3c9c28ac25 100644
--- a/arch/openrisc/kernel/head.S
+++ b/arch/openrisc/kernel/head.S
@@ -19,6 +19,7 @@
 #include <linux/threads.h>
 #include <linux/errno.h>
 #include <linux/init.h>
+#include <linux/serial_reg.h>
 #include <asm/processor.h>
 #include <asm/page.h>
 #include <asm/mmu.h>