diff --git a/src/plugins/gui/project_manager.ml b/src/plugins/gui/project_manager.ml
index 2e60e840184f5cee1e0b02eb2744304e7b43ffe3..d2f20659e5a19492ab859dc060a72019ce930d5a 100644
--- a/src/plugins/gui/project_manager.ml
+++ b/src/plugins/gui/project_manager.ml
@@ -251,7 +251,7 @@ and mk_project_entry window menu ?group p =
 
 and make_project_entries ?filter window menu =
   match projects_list ?filter () with
-  | [] -> assert false
+  | [] -> assert (filter <> None)
   | (pa, _name) :: tl ->
       let mk = mk_project_entry window menu in
       let pa_item = mk pa in