diff --git a/hw/msi.c b/hw/msi.c
index 110859b..12e125f 100644
--- a/hw/msi.c
+++ b/hw/msi.c
@@ -148,6 +148,7 @@ int msi_init(struct PCIDevice *dev, uint8_t offset,
     }
 
     dev->msi_cap = config_offset;
+    dev->msi_cap_size = cap_size;
     dev->cap_present |= QEMU_PCI_CAP_MSI;
 
     pci_set_word(dev->config + msi_flags_off(dev), flags);
@@ -170,14 +171,12 @@ int msi_init(struct PCIDevice *dev, uint8_t offset,
 
 void msi_uninit(struct PCIDevice *dev)
 {
-    uint8_t cap_size;
-
     if (!(dev->cap_present & QEMU_PCI_CAP_MSI))
         return;
 
-    cap_size = msi_cap_sizeof(pci_get_word(dev->config + msi_flags_off(dev)));
-    pci_del_capability(dev, PCI_CAP_ID_MSIX, cap_size);
+    pci_del_capability(dev, PCI_CAP_ID_MSIX, dev->msi_cap_size);
     dev->msi_cap = 0;
+    dev->msi_cap_size = 0;
     dev->cap_present &= ~QEMU_PCI_CAP_MSI;
     MSI_DEV_PRINTF(dev, "uninit\n");
 }
@@ -269,7 +268,7 @@ void msi_write_config(PCIDevice *dev, uint32_t addr, uint32_t val, int len)
     uint32_t pending;
     int i;
 
-    if (!ranges_overlap(addr, len, dev->msi_cap, msi_cap_sizeof(flags))) {
+    if (!ranges_overlap(addr, len, dev->msi_cap, dev->msi_cap_size)) {
         return;
     }
 
diff --git a/hw/pci.h b/hw/pci.h
index a558803..d268806 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -176,8 +176,9 @@ struct PCIDevice {
     /* Version id needed for VMState */
     int32_t version_id;
 
-    /* Offset of MSI capability in config space */
+    /* Offset & size of MSI capability in config space */
     uint8_t msi_cap;
+    uint8_t msi_cap_size;
 
     /* PCI Express */
     PCIExpressDevice exp;