diff --git a/proto/src/system_messages.proto b/proto/src/system_messages.proto
index 196c6aa..3648593 100644
--- a/proto/src/system_messages.proto
+++ b/proto/src/system_messages.proto
@@ -282,6 +282,10 @@
     // Notify the user to set up dream
     NOTE_SETUP_DREAM = 68;
 
+    // Inform the user that MTE override is active.
+    // Package: android
+    NOTE_MTE_OVERRIDE_ENABLED = 69;
+
     // ADD_NEW_IDS_ABOVE_THIS_LINE
     // Legacy IDs with arbitrary values appear below
     // Legacy IDs existed as stable non-conflicting constants prior to the O release