diff --git a/machine.proto b/machine.proto
index f356f77..8594c7a 100644
--- a/machine.proto
+++ b/machine.proto
@@ -19,7 +19,7 @@ message Machine {                                       // `autogenpb:marshal`
         Packages                    wit           = 9;  // packages that are available from mirrors.wit.com
         string                      userAgent     = 10;
         string                      uuid          = 11;
-                                                        // func(string)                blah          = 12;
+        bool                        upgrade       = 12; // upgrade is needed
 }
 
 message Machines {                                      // `autogenpb:marshal` `autogenpb:gui`