diff --git a/hw/pci.c b/hw/pci.c
index 1c95f88..e21098b 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -229,7 +229,7 @@
         VMSTATE_INT32_LE(version_id, PCIDevice),
         VMSTATE_SINGLE(config, PCIDevice, 0, vmstate_info_pci_config,
                        typeof_field(PCIDevice,config)),
-        VMSTATE_INT32_ARRAY_V(irq_state, PCIDevice, 4, 2),
+        VMSTATE_INT32_ARRAY_V(irq_state, PCIDevice, PCI_NUM_PINS, 2),
         VMSTATE_END_OF_LIST()
     }
 };
@@ -389,7 +389,7 @@
     pci_dev->config_read = config_read;
     pci_dev->config_write = config_write;
     bus->devices[devfn] = pci_dev;
-    pci_dev->irq = qemu_allocate_irqs(pci_set_irq, pci_dev, 4);
+    pci_dev->irq = qemu_allocate_irqs(pci_set_irq, pci_dev, PCI_NUM_PINS);
     pci_dev->version_id = 2; /* Current pci device vmstate version */
     return pci_dev;
 }
diff --git a/hw/pci.h b/hw/pci.h
index 93f93fb..476ff59 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -158,6 +158,8 @@
 /* Size of the standard PCI config space */
 #define PCI_CONFIG_SPACE_SIZE 0x100
 
+#define PCI_NUM_PINS 4 /* A-D */
+
 /* Bits in cap_present field. */
 enum {
     QEMU_PCI_CAP_MSIX = 0x1,
@@ -192,7 +194,7 @@
     qemu_irq *irq;
 
     /* Current IRQ levels.  Used internally by the generic PCI code.  */
-    int irq_state[4];
+    int irq_state[PCI_NUM_PINS];
 
     /* Capability bits */
     uint32_t cap_present;