diff --git a/hw/spapr.c b/hw/spapr.c
index bfaf260..cca20f9 100644
--- a/hw/spapr.c
+++ b/hw/spapr.c
@@ -631,8 +631,7 @@ static void ppc_spapr_init(ram_addr_t ram_size,
 
     for (i = 0; i < MAX_SERIAL_PORTS; i++) {
         if (serial_hds[i]) {
-            spapr_vty_create(spapr->vio_bus, SPAPR_VTY_BASE_ADDRESS + i,
-                             serial_hds[i]);
+            spapr_vty_create(spapr->vio_bus, serial_hds[i]);
         }
     }
 
@@ -650,14 +649,14 @@ static void ppc_spapr_init(ram_addr_t ram_size,
         }
 
         if (strcmp(nd->model, "ibmveth") == 0) {
-            spapr_vlan_create(spapr->vio_bus, 0x1000 + i, nd);
+            spapr_vlan_create(spapr->vio_bus, nd);
         } else {
             pci_nic_init_nofail(&nd_table[i], nd->model, NULL);
         }
     }
 
     for (i = 0; i <= drive_get_max_bus(IF_SCSI); i++) {
-        spapr_vscsi_create(spapr->vio_bus, 0x2000 + i);
+        spapr_vscsi_create(spapr->vio_bus);
     }
 
     if (rma_size < (MIN_RMA_SLOF << 20)) {
diff --git a/hw/spapr_llan.c b/hw/spapr_llan.c
index e18d2eb..8313043 100644
--- a/hw/spapr_llan.c
+++ b/hw/spapr_llan.c
@@ -204,12 +204,11 @@ static int spapr_vlan_init(VIOsPAPRDevice *sdev)
     return 0;
 }
 
-void spapr_vlan_create(VIOsPAPRBus *bus, uint32_t reg, NICInfo *nd)
+void spapr_vlan_create(VIOsPAPRBus *bus, NICInfo *nd)
 {
     DeviceState *dev;
 
     dev = qdev_create(&bus->bus, "spapr-vlan");
-    qdev_prop_set_uint32(dev, "reg", reg);
 
     qdev_set_nic_properties(dev, nd);
 
@@ -480,7 +479,7 @@ static target_ulong h_multicast_ctrl(CPUPPCState *env, sPAPREnvironment *spapr,
 }
 
 static Property spapr_vlan_properties[] = {
-    DEFINE_SPAPR_PROPERTIES(VIOsPAPRVLANDevice, sdev, 0x1000, 0x10000000),
+    DEFINE_SPAPR_PROPERTIES(VIOsPAPRVLANDevice, sdev, 0x10000000),
     DEFINE_NIC_PROPERTIES(VIOsPAPRVLANDevice, nicconf),
     DEFINE_PROP_END_OF_LIST(),
 };
diff --git a/hw/spapr_vio.c b/hw/spapr_vio.c
index fccf48b..315ab80 100644
--- a/hw/spapr_vio.c
+++ b/hw/spapr_vio.c
@@ -620,28 +620,22 @@ static void rtas_quiesce(sPAPREnvironment *spapr, uint32_t token,
     rtas_st(rets, 0, 0);
 }
 
-static int spapr_vio_check_reg(VIOsPAPRDevice *sdev)
+static VIOsPAPRDevice *reg_conflict(VIOsPAPRDevice *dev)
 {
-    VIOsPAPRDevice *other_sdev;
+    VIOsPAPRBus *bus = DO_UPCAST(VIOsPAPRBus, bus, dev->qdev.parent_bus);
     DeviceState *qdev;
-    VIOsPAPRBus *sbus;
-
-    sbus = DO_UPCAST(VIOsPAPRBus, bus, sdev->qdev.parent_bus);
+    VIOsPAPRDevice *other;
 
     /*
-     * Check two device aren't given clashing addresses by the user (or some
-     * other mechanism). We have to open code this because we have to check
-     * for matches with devices other than us.
+     * Check for a device other than the given one which is already
+     * using the requested address. We have to open code this because
+     * the given dev might already be in the list.
      */
-    QTAILQ_FOREACH(qdev, &sbus->bus.children, sibling) {
-        other_sdev = DO_UPCAST(VIOsPAPRDevice, qdev, qdev);
+    QTAILQ_FOREACH(qdev, &bus->bus.children, sibling) {
+        other = DO_UPCAST(VIOsPAPRDevice, qdev, qdev);
 
-        if (other_sdev != sdev && other_sdev->reg == sdev->reg) {
-            fprintf(stderr, "vio: %s and %s devices conflict at address %#x\n",
-                    object_get_typename(OBJECT(sdev)),
-                    object_get_typename(OBJECT(qdev)),
-                    sdev->reg);
-            return -EEXIST;
+        if (other != dev && other->reg == dev->reg) {
+            return other;
         }
     }
 
@@ -667,11 +661,30 @@ static int spapr_vio_busdev_init(DeviceState *qdev)
     VIOsPAPRDevice *dev = (VIOsPAPRDevice *)qdev;
     VIOsPAPRDeviceClass *pc = VIO_SPAPR_DEVICE_GET_CLASS(dev);
     char *id;
-    int ret;
 
-    ret = spapr_vio_check_reg(dev);
-    if (ret) {
-        return ret;
+    if (dev->reg != -1) {
+        /*
+         * Explicitly assigned address, just verify that no-one else
+         * is using it.  other mechanism). We have to open code this
+         * rather than using spapr_vio_find_by_reg() because sdev
+         * itself is already in the list.
+         */
+        VIOsPAPRDevice *other = reg_conflict(dev);
+
+        if (other) {
+            fprintf(stderr, "vio: %s and %s devices conflict at address %#x\n",
+                    object_get_typename(OBJECT(qdev)),
+                    object_get_typename(OBJECT(&other->qdev)),
+                    dev->reg);
+            return -1;
+        }
+    } else {
+        /* Need to assign an address */
+        VIOsPAPRBus *bus = DO_UPCAST(VIOsPAPRBus, bus, dev->qdev.parent_bus);
+
+        do {
+            dev->reg = bus->next_reg++;
+        } while (reg_conflict(dev));
     }
 
     /* Don't overwrite ids assigned on the command line */
@@ -731,6 +744,7 @@ VIOsPAPRBus *spapr_vio_bus_init(void)
 
     qbus = qbus_create(&spapr_vio_bus_info, dev, "spapr-vio");
     bus = DO_UPCAST(VIOsPAPRBus, bus, qbus);
+    bus->next_reg = 0x1000;
 
     /* hcall-vio */
     spapr_register_hypercall(H_VIO_SIGNAL, h_vio_signal);
diff --git a/hw/spapr_vio.h b/hw/spapr_vio.h
index 10ab359..87816e4 100644
--- a/hw/spapr_vio.h
+++ b/hw/spapr_vio.h
@@ -32,8 +32,6 @@ enum VIOsPAPR_TCEAccess {
     SPAPR_TCE_RW = 3,
 };
 
-#define SPAPR_VTY_BASE_ADDRESS     0x30000000
-
 #define TYPE_VIO_SPAPR_DEVICE "vio-spapr-device"
 #define VIO_SPAPR_DEVICE(obj) \
      OBJECT_CHECK(VIOsPAPRDevice, (obj), TYPE_VIO_SPAPR_DEVICE)
@@ -82,13 +80,14 @@ struct VIOsPAPRDevice {
     VIOsPAPR_CRQ crq;
 };
 
-#define DEFINE_SPAPR_PROPERTIES(type, field, default_reg, default_dma_window) \
-        DEFINE_PROP_UINT32("reg", type, field.reg, default_reg), \
+#define DEFINE_SPAPR_PROPERTIES(type, field, default_dma_window)       \
+        DEFINE_PROP_UINT32("reg", type, field.reg, -1),                \
         DEFINE_PROP_UINT32("dma-window", type, field.rtce_window_size, \
                            default_dma_window)
 
 struct VIOsPAPRBus {
     BusState bus;
+    uint32_t next_reg;
     int (*init)(VIOsPAPRDevice *dev);
     int (*devnode)(VIOsPAPRDevice *dev, void *fdt, int node_off);
 };
@@ -119,9 +118,9 @@ int spapr_vio_send_crq(VIOsPAPRDevice *dev, uint8_t *crq);
 
 VIOsPAPRDevice *vty_lookup(sPAPREnvironment *spapr, target_ulong reg);
 void vty_putchars(VIOsPAPRDevice *sdev, uint8_t *buf, int len);
-void spapr_vty_create(VIOsPAPRBus *bus, uint32_t reg, CharDriverState *chardev);
-void spapr_vlan_create(VIOsPAPRBus *bus, uint32_t reg, NICInfo *nd);
-void spapr_vscsi_create(VIOsPAPRBus *bus, uint32_t reg);
+void spapr_vty_create(VIOsPAPRBus *bus, CharDriverState *chardev);
+void spapr_vlan_create(VIOsPAPRBus *bus, NICInfo *nd);
+void spapr_vscsi_create(VIOsPAPRBus *bus);
 
 VIOsPAPRDevice *spapr_vty_get_default(VIOsPAPRBus *bus);
 
diff --git a/hw/spapr_vscsi.c b/hw/spapr_vscsi.c
index 538e0b7..037867a 100644
--- a/hw/spapr_vscsi.c
+++ b/hw/spapr_vscsi.c
@@ -918,12 +918,11 @@ static int spapr_vscsi_init(VIOsPAPRDevice *dev)
     return 0;
 }
 
-void spapr_vscsi_create(VIOsPAPRBus *bus, uint32_t reg)
+void spapr_vscsi_create(VIOsPAPRBus *bus)
 {
     DeviceState *dev;
 
     dev = qdev_create(&bus->bus, "spapr-vscsi");
-    qdev_prop_set_uint32(dev, "reg", reg);
 
     qdev_init_nofail(dev);
 }
@@ -946,7 +945,7 @@ static int spapr_vscsi_devnode(VIOsPAPRDevice *dev, void *fdt, int node_off)
 }
 
 static Property spapr_vscsi_properties[] = {
-    DEFINE_SPAPR_PROPERTIES(VSCSIState, vdev, 0x2000, 0x10000000),
+    DEFINE_SPAPR_PROPERTIES(VSCSIState, vdev, 0x10000000),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/hw/spapr_vty.c b/hw/spapr_vty.c
index a30c040..c9674f3 100644
--- a/hw/spapr_vty.c
+++ b/hw/spapr_vty.c
@@ -123,18 +123,17 @@ static target_ulong h_get_term_char(CPUPPCState *env, sPAPREnvironment *spapr,
     return H_SUCCESS;
 }
 
-void spapr_vty_create(VIOsPAPRBus *bus, uint32_t reg, CharDriverState *chardev)
+void spapr_vty_create(VIOsPAPRBus *bus, CharDriverState *chardev)
 {
     DeviceState *dev;
 
     dev = qdev_create(&bus->bus, "spapr-vty");
-    qdev_prop_set_uint32(dev, "reg", reg);
     qdev_prop_set_chr(dev, "chardev", chardev);
     qdev_init_nofail(dev);
 }
 
 static Property spapr_vty_properties[] = {
-    DEFINE_SPAPR_PROPERTIES(VIOsPAPRVTYDevice, sdev, SPAPR_VTY_BASE_ADDRESS, 0),
+    DEFINE_SPAPR_PROPERTIES(VIOsPAPRVTYDevice, sdev, 0),
     DEFINE_PROP_CHR("chardev", VIOsPAPRVTYDevice, chardev),
     DEFINE_PROP_END_OF_LIST(),
 };
