diff --git a/drivers/mailbox/mailbox-test.c b/drivers/mailbox/mailbox-test.c
index 4555d678fadd..51e62817f243 100644
--- a/drivers/mailbox/mailbox-test.c
+++ b/drivers/mailbox/mailbox-test.c
@@ -16,6 +16,7 @@
 #include <linux/platform_device.h>
 #include <linux/poll.h>
 #include <linux/slab.h>
+#include <linux/spinlock.h>
 #include <linux/uaccess.h>
 #include <linux/sched/signal.h>