diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
index df4b81ae54cb..7828656b1b53 100644
--- a/include/fmt/chrono.h
+++ b/include/fmt/chrono.h
@@ -1214,7 +1214,7 @@ template <typename OutputIt, typename Char> class tm_writer {
     char buf[10];
     size_t offset = 0;
     if (year >= 0 && year < 10000) {
-      copy2(buf, digits2(to_unsigned(year / 100)));
+      copy2(buf, digits2(static_cast<size_t>(year / 100)));
     } else {
       offset = 4;
       write_year_extended(year);