diff --git a/apps/su.cpp b/apps/su.cpp
index 60c990fc..0dae9d0f 100644
--- a/apps/su.cpp
+++ b/apps/su.cpp
@@ -62,8 +62,8 @@ Result<int> luna_main(int argc, char** argv)
     }
 
     os::ArgumentParser parser;
-    parser.add_description("Switch to a different user."_sv);
-    parser.add_positional_argument(name, "name"_sv, true);
+    parser.add_description("Switch to a different user (by default, root)."_sv);
+    parser.add_positional_argument(name, "name"_sv, "root"_sv);
     parser.parse(argc, argv);
 
     struct passwd* entry = getpwnam(name.chars());