diff --git a/lib/psci/psci_common.c b/lib/psci/psci_common.c
index ebeb10b..c893476 100644
--- a/lib/psci/psci_common.c
+++ b/lib/psci/psci_common.c
@@ -829,8 +829,11 @@
  ******************************************************************************/
 int psci_validate_mpidr(u_register_t mpidr)
 {
-	if (plat_core_pos_by_mpidr(mpidr) < 0)
+	int pos = plat_core_pos_by_mpidr(mpidr);
+
+	if ((pos < 0) || ((unsigned int)pos >= PLATFORM_CORE_COUNT)) {
 		return PSCI_E_INVALID_PARAMS;
+	}
 
 	return PSCI_E_SUCCESS;
 }
diff --git a/lib/psci/psci_on.c b/lib/psci/psci_on.c
index 6c6b23c..76eb50c 100644
--- a/lib/psci/psci_on.c
+++ b/lib/psci/psci_on.c
@@ -65,13 +65,10 @@
 	unsigned int target_idx;
 
 	/* Calling function must supply valid input arguments */
+	assert(ret >= 0);
+	assert((unsigned int)ret < PLATFORM_CORE_COUNT);
 	assert(ep != NULL);
 
-	if ((ret < 0) || (ret >= (int)PLATFORM_CORE_COUNT)) {
-		ERROR("Unexpected core index.\n");
-		panic();
-	}
-
 	target_idx = (unsigned int)ret;
 
 	/*