diff --git a/drivers/mfd/atmel-smc.c b/drivers/mfd/atmel-smc.c
index 7d77948567d7..0adbd2e796fe 100644
--- a/drivers/mfd/atmel-smc.c
+++ b/drivers/mfd/atmel-smc.c
@@ -12,6 +12,7 @@
  */
 
 #include <linux/mfd/syscon/atmel-smc.h>
+#include <linux/string.h>
 
 /**
  * atmel_smc_cs_conf_init - initialize a SMC CS conf