diff --git a/test/std/utilities/optional/optional.specalg/make_optional_explicit.pass.cpp b/test/std/utilities/optional/optional.specalg/make_optional_explicit.pass.cpp
index e736eb4..3a9aec8 100644
--- a/test/std/utilities/optional/optional.specalg/make_optional_explicit.pass.cpp
+++ b/test/std/utilities/optional/optional.specalg/make_optional_explicit.pass.cpp
@@ -40,7 +40,7 @@
         assert(s == nullptr);
     }
     {
-        auto opt = make_optional<std::string>(4, 'X');
+        auto opt = make_optional<std::string>(4u, 'X');
         assert(*opt == "XXXX");
     }