diff --git a/hw/gt64xxx.c b/hw/gt64xxx.c
index 6af9782d90..1c3425372a 100644
--- a/hw/gt64xxx.c
+++ b/hw/gt64xxx.c
@@ -297,7 +297,11 @@ static void gt64120_pci_mapping(GT64120State *s)
       s->PCI0IO_start = s->regs[GT_PCI0IOLD] << 21;
       s->PCI0IO_length = ((s->regs[GT_PCI0IOHD] + 1) - (s->regs[GT_PCI0IOLD] & 0x7f)) << 21;
       isa_mem_base = s->PCI0IO_start;
-      isa_mmio_init(s->PCI0IO_start, s->PCI0IO_length);
+      if (s->PCI0IO_length) {
+          isa_mmio_setup(&s->PCI0IO_mem, s->PCI0IO_length);
+          memory_region_add_subregion(get_system_memory(), s->PCI0IO_start,
+                                      &s->PCI0IO_mem);
+      }
     }
 }