diff --git a/include/fast_float/ascii_number.h b/include/fast_float/ascii_number.h
index 219c7d3..15a8a20 100644
--- a/include/fast_float/ascii_number.h
+++ b/include/fast_float/ascii_number.h
@@ -529,8 +529,8 @@ from_chars_result_t<UC> parse_int_string(UC const* p, UC const* pend, T& value,
     // this weird workaround is required because:
     // - converting unsigned to signed when its value is greater than signed max is UB pre-C++23.
     // - reinterpret_casting (~i + 1) would work, but it is not constexpr
-    // this is always optimized into a neg instruction.
-    value = T(-std::numeric_limits<T>::max() - T(i - std::numeric_limits<T>::max()));
+    // this is always optimized into a neg instruction (note: T is an integer type)
+    value = T(-std::numeric_limits<T>::max() - T(i - uint64_t(std::numeric_limits<T>::max())));
 #ifdef FASTFLOAT_VISUAL_STUDIO
 #pragma warning(pop)
 #endif