diff --git a/hw/isa-bus.c b/hw/isa-bus.c
index 6c15a31fe8..e9c171210d 100644
--- a/hw/isa-bus.c
+++ b/hw/isa-bus.c
@@ -83,24 +83,11 @@ void isa_init_irq(ISADevice *dev, qemu_irq *p, int isairq)
     dev->nirqs++;
 }
 
-static void isa_init_ioport_one(ISADevice *dev, uint16_t ioport)
-{
-    assert(dev->nioports < ARRAY_SIZE(dev->ioports));
-    dev->ioports[dev->nioports++] = ioport;
-}
-
-static int isa_cmp_ports(const void *p1, const void *p2)
-{
-    return *(uint16_t*)p1 - *(uint16_t*)p2;
-}
-
 void isa_init_ioport_range(ISADevice *dev, uint16_t start, uint16_t length)
 {
-    int i;
-    for (i = start; i < start + length; i++) {
-        isa_init_ioport_one(dev, i);
+    if (dev->ioport_id == 0 || start < dev->ioport_id) {
+        dev->ioport_id = start;
     }
-    qsort(dev->ioports, dev->nioports, sizeof(dev->ioports[0]), isa_cmp_ports);
 }
 
 void isa_init_ioport(ISADevice *dev, uint16_t ioport)
@@ -112,9 +99,7 @@ void isa_register_ioport(ISADevice *dev, MemoryRegion *io, uint16_t start)
 {
     memory_region_add_subregion(isabus->address_space_io, start, io);
     if (dev != NULL) {
-        assert(dev->nio < ARRAY_SIZE(dev->io));
-        dev->io[dev->nio++] = io;
-        isa_init_ioport_range(dev, start, memory_region_size(io));
+        isa_init_ioport(dev, start);
     }
 }
 
@@ -208,8 +193,8 @@ static char *isabus_get_fw_dev_path(DeviceState *dev)
     int off;
 
     off = snprintf(path, sizeof(path), "%s", qdev_fw_name(dev));
-    if (d->nioports) {
-        snprintf(path + off, sizeof(path) - off, "@%04x", d->ioports[0]);
+    if (d->ioport_id) {
+        snprintf(path + off, sizeof(path) - off, "@%04x", d->ioport_id);
     }
 
     return strdup(path);
diff --git a/hw/isa.h b/hw/isa.h
index 432d17ab26..c5c2618c74 100644
--- a/hw/isa.h
+++ b/hw/isa.h
@@ -13,12 +13,9 @@ typedef struct ISADeviceInfo ISADeviceInfo;
 
 struct ISADevice {
     DeviceState qdev;
-    MemoryRegion *io[32];
     uint32_t isairq[2];
-    uint16_t ioports[32];
     int nirqs;
-    int nioports;
-    int nio;
+    int ioport_id;
 };
 
 typedef int (*isa_qdev_initfn)(ISADevice *dev);