diff --git a/include/plat/common/platform.h b/include/plat/common/platform.h
index 9efb2fd..332cfca 100644
--- a/include/plat/common/platform.h
+++ b/include/plat/common/platform.h
@@ -237,7 +237,7 @@
 void plat_psci_stat_accounting_stop(const psci_power_state_t *state_info);
 u_register_t plat_psci_stat_get_residency(unsigned int lvl,
 			const psci_power_state_t *state_info,
-			int last_cpu_idx);
+			unsigned int last_cpu_idx);
 plat_local_state_t plat_get_target_pwr_state(unsigned int lvl,
 			const plat_local_state_t *states,
 			unsigned int ncpu);