diff --git a/drivers/gpio/wm8994-gpio.c b/drivers/gpio/wm8994-gpio.c
index de28b4a..7607cc6 100644
--- a/drivers/gpio/wm8994-gpio.c
+++ b/drivers/gpio/wm8994-gpio.c
@@ -13,6 +13,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/gpio.h>
 #include <linux/mfd/core.h>