diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c
index ebd0e75a3e4d..e2d1055fb814 100644
--- a/drivers/char/tpm/tpm_tis.c
+++ b/drivers/char/tpm/tpm_tis.c
@@ -30,6 +30,7 @@
 #include <linux/freezer.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/kernel.h>
 #include "tpm.h"
 #include "tpm_tis_core.h"
 
@@ -365,7 +366,7 @@ static struct pnp_driver tis_pnp_driver = {
 	},
 };
 
-#define TIS_HID_USR_IDX sizeof(tpm_pnp_tbl)/sizeof(struct pnp_device_id) -2
+#define TIS_HID_USR_IDX (ARRAY_SIZE(tpm_pnp_tbl) - 2)
 module_param_string(hid, tpm_pnp_tbl[TIS_HID_USR_IDX].id,
 		    sizeof(tpm_pnp_tbl[TIS_HID_USR_IDX].id), 0444);
 MODULE_PARM_DESC(hid, "Set additional specific HID for this driver to probe");