diff --git a/hw/isa/vt82c686.c b/hw/isa/vt82c686.c
index a6f5a0843d..30fe02f4c6 100644
--- a/hw/isa/vt82c686.c
+++ b/hw/isa/vt82c686.c
@@ -29,12 +29,11 @@
 typedef struct SuperIOConfig {
     uint8_t regs[0x100];
     uint8_t index;
-    uint8_t data;
+    MemoryRegion io;
 } SuperIOConfig;
 
 struct VT82C686BISAState {
     PCIDevice dev;
-    MemoryRegion superio;
     SuperIOConfig superio_cfg;
 };
 
@@ -128,8 +127,9 @@ static void vt82c686b_write_config(PCIDevice *d, uint32_t addr,
 
     trace_via_isa_write(addr, val, len);
     pci_default_write_config(d, addr, val, len);
-    if (addr == 0x85) {  /* enable or disable super IO configure */
-        memory_region_set_enabled(&s->superio, val & 0x2);
+    if (addr == 0x85) {
+        /* BIT(1): enable or disable superio config io ports */
+        memory_region_set_enabled(&s->superio_cfg.io, val & BIT(1));
     }
 }
 
@@ -311,15 +311,15 @@ static void vt82c686b_realize(PCIDevice *d, Error **errp)
         }
     }
 
-    memory_region_init_io(&s->superio, OBJECT(d), &superio_cfg_ops,
-                          &s->superio_cfg, "superio", 2);
-    memory_region_set_enabled(&s->superio, false);
+    memory_region_init_io(&s->superio_cfg.io, OBJECT(d), &superio_cfg_ops,
+                          &s->superio_cfg, "superio_cfg", 2);
+    memory_region_set_enabled(&s->superio_cfg.io, false);
     /*
      * The floppy also uses 0x3f0 and 0x3f1.
      * But we do not emulate a floppy, so just set it here.
      */
     memory_region_add_subregion(isa_bus->address_space_io, 0x3f0,
-                                &s->superio);
+                                &s->superio_cfg.io);
 }
 
 static void via_class_init(ObjectClass *klass, void *data)