diff --git a/drivers/scmi-msg/clock.c b/drivers/scmi-msg/clock.c
index e96cede6e..85bf7d24c 100644
--- a/drivers/scmi-msg/clock.c
+++ b/drivers/scmi-msg/clock.c
@@ -361,7 +361,7 @@ static const scmi_msg_handler_t scmi_clock_handler_table[] = {
 	[SCMI_CLOCK_CONFIG_SET] = scmi_clock_config_set,
 };
 
-static bool message_id_is_supported(size_t message_id)
+static bool message_id_is_supported(unsigned int message_id)
 {
 	return (message_id < ARRAY_SIZE(scmi_clock_handler_table)) &&
 	       (scmi_clock_handler_table[message_id] != NULL);
diff --git a/drivers/scmi-msg/power_domain.c b/drivers/scmi-msg/power_domain.c
index c4e1289a2..87c41dd8e 100644
--- a/drivers/scmi-msg/power_domain.c
+++ b/drivers/scmi-msg/power_domain.c
@@ -19,7 +19,7 @@
 #pragma weak plat_scmi_pd_statistics
 #pragma weak plat_scmi_pd_get_attributes
 
-static bool message_id_is_supported(size_t message_id);
+static bool message_id_is_supported(unsigned int message_id);
 
 size_t plat_scmi_pd_count(unsigned int agent_id __unused)
 {
@@ -219,7 +219,7 @@ static const scmi_msg_handler_t scmi_pd_handler_table[] = {
 	[SCMI_PD_STATE_GET] = scmi_pd_state_get,
 };
 
-static bool message_id_is_supported(size_t message_id)
+static bool message_id_is_supported(unsigned int message_id)
 {
 	return (message_id < ARRAY_SIZE(scmi_pd_handler_table)) &&
 	       (scmi_pd_handler_table[message_id] != NULL);