diff --git a/drivers/char/rocket.c b/drivers/char/rocket.c
index 63d5b62..0e29a23 100644
--- a/drivers/char/rocket.c
+++ b/drivers/char/rocket.c
@@ -73,6 +73,7 @@
 #include <linux/tty_driver.h>
 #include <linux/tty_flip.h>
 #include <linux/serial.h>
+#include <linux/smp_lock.h>
 #include <linux/string.h>
 #include <linux/fcntl.h>
 #include <linux/ptrace.h>