diff --git a/hw/pci.c b/hw/pci.c
index 5cf50e056..b462bd624 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -524,7 +524,14 @@ static void pci_update_mappings(PCIDevice *d)
                        mappings, we handle specific values as invalid
                        mappings. */
                     if (last_addr <= new_addr || new_addr == 0 ||
-                        last_addr == PCI_BAR_UNMAPPED) {
+                        last_addr == PCI_BAR_UNMAPPED ||
+
+                        /* Now pcibus_t is 64bit.
+                         * Check if 32 bit BAR wrap around explicitly.
+                         * Without this, PC ide doesn't work well.
+                         * TODO: remove this work around.
+                         */
+                        last_addr >= UINT32_MAX) {
                         new_addr = PCI_BAR_UNMAPPED;
                     }
                 } else {
diff --git a/hw/pci.h b/hw/pci.h
index fa2077dda..305c030f9 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -71,8 +71,8 @@ extern target_phys_addr_t pci_mem_base;
 #define PCI_DEVICE_ID_VIRTIO_BALLOON     0x1002
 #define PCI_DEVICE_ID_VIRTIO_CONSOLE     0x1003
 
-typedef uint32_t pcibus_t;
-#define FMT_PCIBUS                      PRIx32
+typedef uint64_t pcibus_t;
+#define FMT_PCIBUS                      PRIx64
 
 typedef void PCIConfigWriteFunc(PCIDevice *pci_dev,
                                 uint32_t address, uint32_t data, int len);