diff --git a/src/superio/ite/common/env_ctrl.c b/src/superio/ite/common/env_ctrl.c
index b3312e60bf..1e313ce715 100644
--- a/src/superio/ite/common/env_ctrl.c
+++ b/src/superio/ite/common/env_ctrl.c
@@ -98,7 +98,7 @@ static void enable_peci(const u16 base, const u8 tmpin)
  * Set up External Temperature to read via thermal diode/resistor
  * into TMPINx register
  */
-static void enable_tmpin(const u16 base, const int tmpin,
+static void enable_tmpin(const u16 base, const u8 tmpin,
 			 const enum ite_ec_thermal_mode mode)
 {
 	u8 reg;