diff --git a/lib/utils/irqchip/plic.c b/lib/utils/irqchip/plic.c
index 73d77889..4df90208 100644
--- a/lib/utils/irqchip/plic.c
+++ b/lib/utils/irqchip/plic.c
@@ -38,13 +38,13 @@ static void plic_set_priority(const struct plic_data *plic, u32 source, u32 val)
 
 void plic_priority_save(const struct plic_data *plic, u8 *priority)
 {
-	for (u32 i = 0; i < plic->num_src; i++)
+	for (u32 i = 1; i <= plic->num_src; i++)
 		priority[i] = plic_get_priority(plic, i);
 }
 
 void plic_priority_restore(const struct plic_data *plic, const u8 *priority)
 {
-	for (u32 i = 0; i < plic->num_src; i++)
+	for (u32 i = 1; i <= plic->num_src; i++)
 		plic_set_priority(plic, i, priority[i]);
 }