diff --git a/include/fmt/format.h b/include/fmt/format.h
index 124f022b..37f46686 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -2585,14 +2585,14 @@ template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value&&
 FMT_CONSTEXPR20 bool isfinite(T value) {
   constexpr T inf = T(std::numeric_limits<double>::infinity());
   if (is_constant_evaluated())
-    return !detail::isnan(value) && value != inf && value != -inf;
+    return !detail::isnan(value) && value < inf && value > -inf;
   return std::isfinite(value);
 }
 template <typename T, FMT_ENABLE_IF(!has_isfinite<T>::value)>
 FMT_CONSTEXPR bool isfinite(T value) {
   T inf = T(std::numeric_limits<double>::infinity());
   // std::isfinite doesn't support __float128.
-  return !detail::isnan(value) && value != inf && value != -inf;
+  return !detail::isnan(value) && value < inf && value > -inf;
 }
 
 template <typename T, FMT_ENABLE_IF(is_floating_point<T>::value)>