diff --git a/hw/intc/sifive_plic.c b/hw/intc/sifive_plic.c
index af4ae3630e..f864efa761 100644
--- a/hw/intc/sifive_plic.c
+++ b/hw/intc/sifive_plic.c
@@ -180,8 +180,10 @@ static void sifive_plic_write(void *opaque, hwaddr addr, uint64_t value,
     if (addr_between(addr, plic->priority_base, plic->num_sources << 2)) {
         uint32_t irq = ((addr - plic->priority_base) >> 2) + 1;
 
-        plic->source_priority[irq] = value & 7;
-        sifive_plic_update(plic);
+        if (value <= plic->num_priorities) {
+            plic->source_priority[irq] = value;
+            sifive_plic_update(plic);
+        }
     } else if (addr_between(addr, plic->pending_base,
                             plic->num_sources >> 3)) {
         qemu_log_mask(LOG_GUEST_ERROR,