diff --git a/plat/arm/board/morello/morello_bl31_setup.c b/plat/arm/board/morello/morello_bl31_setup.c
index a044212..e04587d 100644
--- a/plat/arm/board/morello/morello_bl31_setup.c
+++ b/plat/arm/board/morello/morello_bl31_setup.c
@@ -19,7 +19,7 @@
 	.ring_doorbell = &mhu_ring_doorbell
 };
 
-scmi_channel_plat_info_t *plat_css_get_scmi_info(int channel_id)
+scmi_channel_plat_info_t *plat_css_get_scmi_info(unsigned int channel_id)
 {
 	return &morello_scmi_plat_info;
 }