diff --git a/apps/ls.cpp b/apps/ls.cpp
index 646a3c61..4890ce1a 100644
--- a/apps/ls.cpp
+++ b/apps/ls.cpp
@@ -113,7 +113,7 @@ Result<int> luna_main(int argc, char** argv)
     else
     {
         os::eprintln("%s: unknown sort type: %s", argv[0], sort_type.chars());
-        return 1;
+        parser.short_usage(argv[0]);
     }
 
     if (os::FileSystem::is_directory(pathname, follow_symlink_args) && !list_directories)
diff --git a/libos/include/os/ArgumentParser.h b/libos/include/os/ArgumentParser.h
index 392ed9b2..1816da88 100644
--- a/libos/include/os/ArgumentParser.h
+++ b/libos/include/os/ArgumentParser.h
@@ -41,6 +41,8 @@ namespace os
          * Should not be used otherwise. */
         void add_system_program_info(StringView name);
 
+        void short_usage(StringView program_name);
+
       private:
         struct PositionalArgument
         {
@@ -69,7 +71,6 @@ namespace os
         };
 
         Result<void> usage(StringView program_name);
-        void short_usage(StringView program_name);
 
         void version();