diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
index abf3671e5b59..76bbb909058b 100644
--- a/include/fmt/chrono.h
+++ b/include/fmt/chrono.h
@@ -364,7 +364,7 @@ void write_codecvt(codecvt_result<CodeUnit>& out, string_view in,
 template <typename OutputIt>
 auto write_encoded_tm_str(OutputIt out, string_view in, const std::locale& loc)
     -> OutputIt {
-  if (detail::use_utf8 && loc != get_classic_locale()) {
+  if (const_check(detail::use_utf8) && loc != get_classic_locale()) {
     // char16_t and char32_t codecvts are broken in MSVC (linkage errors) and
     // gcc-4.
 #if FMT_MSC_VERSION != 0 ||  \