diff --git a/include/fmt/format.h b/include/fmt/format.h
index e39bec68..9dda5662 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -369,10 +369,6 @@ class uint128_fallback {
  private:
   uint64_t lo_, hi_;
 
-#ifdef _WIN32
-  friend uint128_fallback umul128(uint64_t x, uint64_t y) noexcept;
-#endif
-
  public:
   constexpr uint128_fallback(uint64_t hi, uint64_t lo) : lo_(lo), hi_(hi) {}
   constexpr uint128_fallback(uint64_t value = 0) : lo_(value), hi_(0) {}
@@ -380,6 +376,9 @@ class uint128_fallback {
   constexpr uint64_t high() const noexcept { return hi_; }
   constexpr uint64_t low() const noexcept { return lo_; }
 
+  uint64_t& high() { return hi_; }
+  uint64_t& low() { return lo_; }
+
   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
   constexpr explicit operator T() const {
     return static_cast<T>(lo_);
@@ -1491,7 +1490,7 @@ inline uint128_fallback umul128(uint64_t x, uint64_t y) noexcept {
   return {static_cast<uint64_t>(p >> 64), static_cast<uint64_t>(p)};
 #elif defined(_MSC_VER) && defined(_M_X64)
   auto result = uint128_fallback();
-  result.lo_ = _umul128(x, y, &result.hi_);
+  result.low() = _umul128(x, y, &result.high());
   return result;
 #else
   const uint64_t mask = static_cast<uint64_t>(max_value<uint32_t>());