diff --git a/Sources/TelemetryClient/SignalManager.swift b/Sources/TelemetryClient/SignalManager.swift
index 37ac4c6..f0c9de5 100644
--- a/Sources/TelemetryClient/SignalManager.swift
+++ b/Sources/TelemetryClient/SignalManager.swift
@@ -203,7 +203,7 @@ private extension SignalManager {
     var defaultUserIdentifier: String {
         guard configuration.defaultUser == nil else { return configuration.defaultUser! }
 
-        #if os(iOS) || os(tvOS)
+        #if os(iOS) || os(tvOS) || os(xrOS)
             return UIDevice.current.identifierForVendor?.uuidString ?? "unknown user \(DefaultSignalPayload.systemVersion) \(DefaultSignalPayload.buildNumber)"
         #elseif os(watchOS)
             if #available(watchOS 6.2, *) {