diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index 9c5eea3..9ded667 100644
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -31,6 +31,7 @@
 #include <linux/seq_file.h>
 #include <linux/bitops.h>
 #include <linux/clocksource.h>
+#include <linux/slab.h>
 
 #include <asm/current.h>
 #include <asm/uaccess.h>