diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
index f99461fa..54e28488 100644
--- a/include/fmt/chrono.h
+++ b/include/fmt/chrono.h
@@ -203,7 +203,7 @@ To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
     }
     const auto min1 =
         (std::numeric_limits<IntermediateRep>::min)() / Factor::num;
-    if (count < min1) {
+    if (std::is_unsigned<IntermediateRep>::value || count < min1) {
       ec = 1;
       return {};
     }