diff --git a/include/fmt/std.h b/include/fmt/std.h
index 4b22eda1..29667b2b 100644
--- a/include/fmt/std.h
+++ b/include/fmt/std.h
@@ -98,7 +98,7 @@ FMT_END_NAMESPACE
 FMT_BEGIN_NAMESPACE
 template <typename T, typename Char>
 struct formatter<std::optional<T>, Char,
-                 std::enable_if_t<is_formattable<T>::value>> {
+                 std::enable_if_t<is_formattable<T, Char>::value>> {
  private:
   formatter<T, Char> underlying_;
   static constexpr basic_string_view<Char> optional =
diff --git a/test/std-test.cc b/test/std-test.cc
index f30c514b..39aac5a2 100644
--- a/test/std-test.cc
+++ b/test/std-test.cc
@@ -12,7 +12,6 @@
 
 #include "fmt/os.h"  // fmt::system_category
 #include "fmt/ranges.h"
-#include "fmt/xchar.h"
 #include "gtest-extra.h"  // StartsWith
 
 using testing::StartsWith;
@@ -53,7 +52,7 @@ TEST(std_test, thread_id) {
 
 TEST(std_test, optional) {
 #ifdef __cpp_lib_optional
-  EXPECT_EQ(fmt::format(L"{}", std::optional<int>{}), L"none");
+  EXPECT_EQ(fmt::format("{}", std::optional<int>{}), "none");
   EXPECT_EQ(fmt::format("{}", std::pair{1, "second"}), "(1, \"second\")");
   EXPECT_EQ(fmt::format("{}", std::vector{std::optional{1}, std::optional{2},
                                           std::optional{3}}),
diff --git a/test/xchar-test.cc b/test/xchar-test.cc
index 1deab2d0..022646da 100644
--- a/test/xchar-test.cc
+++ b/test/xchar-test.cc
@@ -16,6 +16,7 @@
 #include "fmt/color.h"
 #include "fmt/ostream.h"
 #include "fmt/ranges.h"
+#include "fmt/std.h"
 #include "gtest-extra.h"  // Contains
 #include "util.h"         // get_locale
 
@@ -588,4 +589,12 @@ TEST(locale_test, sign) {
   EXPECT_EQ(fmt::format(std::locale(), L"{:L}", -50), L"-50");
 }
 
+TEST(std_test_xchar, optional) {
+#  ifdef __cpp_lib_optional
+  EXPECT_EQ(fmt::format(L"{}", std::optional{L'C'}), L"optional(\'C\')");
+  EXPECT_EQ(fmt::format(L"{}", std::optional{std::wstring{L"wide string"}}),
+            L"optional(\"wide string\")");
+#  endif
+}
+
 #endif  // FMT_STATIC_THOUSANDS_SEPARATOR