diff --git a/pkg/pci/address/address.go b/pkg/pci/address/address.go
index 65e8cca..660238c 100644
--- a/pkg/pci/address/address.go
+++ b/pkg/pci/address/address.go
@@ -13,7 +13,7 @@ import (
 
 var (
 	regexAddress *regexp.Regexp = regexp.MustCompile(
-		`^(([0-9a-f]{0,8}):)?([0-9a-f]{2}):([0-9a-f]{2})\.([0-9a-f]{1})$`,
+		`^((1?[0-9a-f]{0,4}):)?([0-9a-f]{2}):([0-9a-f]{2})\.([0-9a-f]{1})$`,
 	)
 )
 
@@ -32,7 +32,7 @@ func (addr *Address) String() string {
 
 // FromString returns [Address] from an address string in either
 // $BUS:$DEVICE.$FUNCTION (BDF) format or a full PCI address that
-// includes the $DOMAIN: $DOMAIN:$BUS:$DEVICE.$FUNCTION.
+// includes the domain: $DOMAIN:$BUS:$DEVICE.$FUNCTION.
 //
 // If the address string isn't a valid PCI address, then nil is returned.
 func FromString(address string) *Address {
diff --git a/pkg/pci/address/address_test.go b/pkg/pci/address/address_test.go
index daf0eaa..54c873e 100644
--- a/pkg/pci/address/address_test.go
+++ b/pkg/pci/address/address_test.go
@@ -62,6 +62,16 @@ func TestPCIAddressFromString(t *testing.T) {
 				Function: "a",
 			},
 		},
+		{
+			// PCI-X / PCI Express extensions may use 5-digit domain
+			addrStr: "10000:03:00.A",
+			expected: &pciaddr.Address{
+				Domain:   "10000",
+				Bus:      "03",
+				Device:   "00",
+				Function: "a",
+			},
+		},
 	}
 	for x, test := range tests {
 		got := pciaddr.FromString(test.addrStr)