diff --git a/lib/src/usage_impl.dart b/lib/src/usage_impl.dart
index 40f2e13..97dda11 100644
--- a/lib/src/usage_impl.dart
+++ b/lib/src/usage_impl.dart
@@ -236,6 +236,11 @@ class AnalyticsImpl implements Analytics {
   @override
   String get clientId => properties['clientId'] ??= Uuid().generateV4();
 
+  @override
+  set clientId(String value) {
+    properties['clientId'] = value;
+  }
+
   /// Send raw data to analytics. Callers should generally use one of the typed
   /// methods (`sendScreenView`, `sendEvent`, ...).
   ///
diff --git a/lib/usage.dart b/lib/usage.dart
index 1f1188a..ac7a890 100644
--- a/lib/usage.dart
+++ b/lib/usage.dart
@@ -68,6 +68,9 @@ abstract class Analytics {
   /// computer sending analytics data.
   String get clientId;
 
+  // Set a custom client id. 
+  set clientId(String value);
+
   /// Sends a screen view hit to Google Analytics.
   ///
   /// [parameters] can be any analytics key/value pair. Useful
@@ -219,6 +222,9 @@ class AnalyticsMock implements Analytics {
   @override
   String get clientId => '00000000-0000-4000-0000-000000000000';
 
+  @override
+  set clientId(String value) {}
+
   @override
   Future sendScreenView(String viewName, {Map<String, String>? parameters}) {
     parameters ??= <String, String>{};
diff --git a/test/src/common.dart b/test/src/common.dart
index b08d89b..958e704 100644
--- a/test/src/common.dart
+++ b/test/src/common.dart
@@ -26,12 +26,22 @@ class AnalyticsImplMock extends AnalyticsImpl {
             applicationName: 'Test App', applicationVersion: '0.1');
 
   String get last => mockPostHandler.last;
+
+  @override
+  set clientId(String value) {
+    properties['clientId'] = value;
+  }
 }
 
 class StallingAnalyticsImplMock extends AnalyticsImpl {
   StallingAnalyticsImplMock(String trackingId, {Map<String, dynamic>? props})
       : super(trackingId, MockProperties(props), StallingPostHandler(),
             applicationName: 'Test App', applicationVersion: '0.1');
+
+  @override
+  set clientId(String value) {
+    properties['clientId'] = value;
+  }
 }
 
 class StallingPostHandler extends PostHandler {