diff --git a/src/Core/Constants.cs b/src/Core/Constants.cs
index 10c68ddc42..e53ade8bfc 100644
--- a/src/Core/Constants.cs
+++ b/src/Core/Constants.cs
@@ -148,6 +148,7 @@ public static class FeatureFlagKeys
     public const string DesktopMigrationMilestone1 = "desktop-ui-migration-milestone-1";
     public const string DesktopMigrationMilestone2 = "desktop-ui-migration-milestone-2";
     public const string DesktopMigrationMilestone3 = "desktop-ui-migration-milestone-3";
+    public const string DesktopMigrationMilestone4 = "desktop-ui-migration-milestone-4";
 
     /* Auth Team */
     public const string TwoFactorExtensionDataPersistence = "pm-9115-two-factor-extension-data-persistence";