diff --git a/plat/arm/common/arm_pm.c b/plat/arm/common/arm_pm.c
index d0350d6..a8289ff 100644
--- a/plat/arm/common/arm_pm.c
+++ b/plat/arm/common/arm_pm.c
@@ -30,11 +30,11 @@
 int arm_validate_power_state(unsigned int power_state,
 			    psci_power_state_t *req_state)
 {
-	int pstate = psci_get_pstate_type(power_state);
-	int pwr_lvl = psci_get_pstate_pwrlvl(power_state);
-	int i;
+	unsigned int pstate = psci_get_pstate_type(power_state);
+	unsigned int pwr_lvl = psci_get_pstate_pwrlvl(power_state);
+	unsigned int i;
 
-	assert(req_state);
+	assert(req_state > 0U);
 
 	if (pwr_lvl > PLAT_MAX_PWR_LVL)
 		return PSCI_E_INVALID_PARAMS;
@@ -59,7 +59,7 @@
 	/*
 	 * We expect the 'state id' to be zero.
 	 */
-	if (psci_get_pstate_id(power_state))
+	if (psci_get_pstate_id(power_state) != 0U)
 		return PSCI_E_INVALID_PARAMS;
 
 	return PSCI_E_SUCCESS;