diff --git a/App Store Receipt Checker/MACAddress.swift b/App Store Receipt Checker/MACAddress.swift
index 4e9dfc3..8b8a6ca 100644
--- a/App Store Receipt Checker/MACAddress.swift	
+++ b/App Store Receipt Checker/MACAddress.swift	
@@ -13,14 +13,14 @@ import IOKit.network
 
 public extension ProcessInfo {
 
-    func macAddress() -> [UInt8]? {
+    var macAddress: [UInt8]? {
         // create matching services dictionary for IOKit to enumerate — this is some UGLY swift, since we're switching from and then back to `CFDictionary`s
         guard var matchingDictionary = IOServiceMatching(kIOEthernetInterfaceClass) as? [String : CFTypeRef] else { return nil }
         matchingDictionary[kIOPropertyMatchKey] = [kIOPrimaryInterface: true] as CFDictionary // there can be only one
 
         // create ethernet iterator
         var ioIterator = io_iterator_t(MACH_PORT_NULL)
-        guard IOServiceGetMatchingServices(kIOMasterPortDefault, matchingDictionary as CFDictionary, &ioIterator) != 0 else { return nil }
+        guard IOServiceGetMatchingServices(kIOMasterPortDefault, matchingDictionary as CFDictionary, &ioIterator) == noErr else { return nil }
         if ioIterator == MACH_PORT_NULL { return nil } // "If NULL is returned, the iteration was successful but found no matching services."
         defer { IOObjectRelease(ioIterator) }
 
@@ -31,7 +31,7 @@ public extension ProcessInfo {
 
         // get that service's parent because the MAC address is there, for reasons
         var parentService = io_object_t(MACH_PORT_NULL)
-        guard IORegistryEntryGetParentEntry(firstAndOnlyService, kIOServicePlane, &parentService) != 0 else { return nil }
+        guard IORegistryEntryGetParentEntry(firstAndOnlyService, kIOServicePlane, &parentService) == noErr else { return nil }
         defer { IOObjectRelease(parentService) }
 
         // finally, get the darn MAC
diff --git a/App Store Receipt Checker/Store Receipts/Receipt.swift b/App Store Receipt Checker/Store Receipts/Receipt.swift
index 1750563..a702647 100644
--- a/App Store Receipt Checker/Store Receipts/Receipt.swift	
+++ b/App Store Receipt Checker/Store Receipts/Receipt.swift	
@@ -246,7 +246,7 @@ private extension Receipt { // MARK: private methods
     }
 
     private func checkReceiptHash() throws {
-        guard let macAddressBytes = ProcessInfo.processInfo.macAddress() else { throw Errors.cannotGetMacAddress }
+        guard let macAddressBytes = ProcessInfo.processInfo.macAddress else { throw Errors.cannotGetMacAddress }
         guard let opaqueValueRawBytes = appReceiptEntries[.opaqueValue]?.rawValue.bytes else { throw Errors.receiptMalformedMissingOpaqueValue }
         guard let bundleIdentifierRawBytes = appReceiptEntries[.bundleIdentifier]?.rawValue.bytes else { throw Errors.receiptMissingBundleIdentifier }