diff --git a/test/filesystem_test.cpp b/test/filesystem_test.cpp
index a951101..a985dc0 100644
--- a/test/filesystem_test.cpp
+++ b/test/filesystem_test.cpp
@@ -462,16 +462,20 @@ TEST_CASE("30.10.8.4.7 path generic format observers", "[filesystem][path][fs.pa
 {
 #ifdef GHC_OS_WINDOWS
     CHECK(fs::u8path("\xc3\xa4\\\xe2\x82\xac").generic_string() == std::string("\xc3\xa4/\xe2\x82\xac"));
+#ifndef USE_STD_FS
     auto t = fs::u8path("\xc3\xa4\\\xe2\x82\xac").generic_string<char, std::char_traits<char>, TestAllocator<char>>()
     CHECK(t.c_str() == std::string("\xc3\xa4/\xe2\x82\xac"));
+#endif
     CHECK(fs::u8path("\xc3\xa4\\\xe2\x82\xac").generic_wstring() == std::wstring(L"\U000000E4/\U000020AC"));
     CHECK(fs::u8path("\xc3\xa4\\\xe2\x82\xac").generic_u8string() == std::string("\xc3\xa4/\xe2\x82\xac"));
     CHECK(fs::u8path("\xc3\xa4\\\xe2\x82\xac").generic_u16string() == std::u16string(u"\u00E4/\u20AC"));
     CHECK(fs::u8path("\xc3\xa4\\\xe2\x82\xac").generic_u32string() == std::u32string(U"\U000000E4/\U000020AC"));
 #else
     CHECK(fs::u8path("\xc3\xa4/\xe2\x82\xac").generic_string() == std::string(u8"\xc3\xa4/\xe2\x82\xac"));
+#ifndef USE_STD_FS
     auto t = fs::u8path("\xc3\xa4/\xe2\x82\xac").generic_string<char, std::char_traits<char>, TestAllocator<char>>();
     CHECK(t.c_str() == std::string(u8"\xc3\xa4/\xe2\x82\xac"));
+#endif
     CHECK(fs::u8path("\xc3\xa4/\xe2\x82\xac").generic_wstring() == std::wstring(L"ä/€"));
     CHECK(fs::u8path("\xc3\xa4/\xe2\x82\xac").generic_u8string() == std::string(u8"\xc3\xa4/\xe2\x82\xac"));
     CHECK(fs::u8path("\xc3\xa4/\xe2\x82\xac").generic_u16string() == std::u16string(u"\u00E4/\u20AC"));