diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index cd6c00c0b3..5988656279 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -293,6 +293,7 @@ static void pc_init1(MachineState *machine,
     } else {
         isa_bus = isa_bus_new(NULL, system_memory, system_io,
                               &error_abort);
+        isa_bus_register_input_irqs(isa_bus, x86ms->gsi);
 
         rtc_state = isa_new(TYPE_MC146818_RTC);
         qdev_prop_set_int32(DEVICE(rtc_state), "base_year", 2000);
@@ -301,7 +302,6 @@ static void pc_init1(MachineState *machine,
         i8257_dma_init(isa_bus, 0);
         pcms->hpet_enabled = false;
     }
-    isa_bus_register_input_irqs(isa_bus, x86ms->gsi);
 
     if (x86ms->pic == ON_OFF_AUTO_ON || x86ms->pic == ON_OFF_AUTO_AUTO) {
         pc_i8259_create(isa_bus, gsi_state->i8259_irq);
diff --git a/hw/isa/piix3.c b/hw/isa/piix3.c
index 616f5418fa..3e7c42fa68 100644
--- a/hw/isa/piix3.c
+++ b/hw/isa/piix3.c
@@ -278,6 +278,8 @@ static void pci_piix3_realize(PCIDevice *dev, Error **errp)
     memory_region_add_subregion_overlap(pci_address_space_io(dev),
                                         PIIX_RCR_IOPORT, &d->rcr_mem, 1);
 
+    isa_bus_register_input_irqs(isa_bus, d->isa_irqs_in);
+
     i8257_dma_init(isa_bus, 0);
 
     /* RTC */