diff --git a/generation/WinSDK/enums.json b/generation/WinSDK/enums.json
index 1d4fb97a2..e04e16656 100644
--- a/generation/WinSDK/enums.json
+++ b/generation/WinSDK/enums.json
@@ -11480,6 +11480,7 @@
   },
   {
     "name": "REGISTER_NOTIFICATION_FLAGS",
+    "flags": true,
     "members": [
       {
         "name": "DEVICE_NOTIFY_SERVICE_HANDLE",
diff --git a/scripts/ChangesSinceLastRelease.txt b/scripts/ChangesSinceLastRelease.txt
index c2701c38d..2933b0ea8 100644
--- a/scripts/ChangesSinceLastRelease.txt
+++ b/scripts/ChangesSinceLastRelease.txt
@@ -61918,3 +61918,5 @@ Windows.Win32.UI.WindowsAndMessaging.Apis.EWX_FORCE removed
 Windows.Win32.UI.WindowsAndMessaging.Apis.EWX_FORCEIFHUNG removed
 Windows.Win32.UI.WindowsAndMessaging.Apis.EWX_QUICKRESOLVE removed
 Windows.Win32.UI.WindowsAndMessaging.Apis.EWX_SYSTEM_INITIATED removed
+# Fixed #1640.
+Windows.Win32.UI.WindowsAndMessaging.REGISTER_NOTIFICATION_FLAGS :  => [Flags]