diff --git a/scripts/update_appup.escript b/scripts/update_appup.escript
index b84e210fa..a8d9d4828 100755
--- a/scripts/update_appup.escript
+++ b/scripts/update_appup.escript
@@ -531,6 +531,7 @@ index_app(AppFile) ->
               , modules       = Modules
               }}.
 
+diff_app(_, gpb, _, _) -> ok; %% gpb is not a runtime app
 diff_app(UpOrDown, App,
          #app{version = NewVersion, modules = NewModules},
          #app{version = OldVersion, modules = OldModules}) ->