diff --git a/include/fast_float/parse_number.h b/include/fast_float/parse_number.h
index 416f5f7..71989f6 100644
--- a/include/fast_float/parse_number.h
+++ b/include/fast_float/parse_number.h
@@ -373,6 +373,18 @@ integer_times_pow10(int64_t mantissa, int decimal_exponent) noexcept {
 
 // the following overloads are here to avoid surprising ambiguity for int,
 // unsigned, etc.
+#if !defined(_MSC_VER)
+FASTFLOAT_CONSTEXPR20 inline double
+integer_times_pow10(unsigned long long mantissa,
+                    int decimal_exponent) noexcept {
+  return integer_times_pow10(static_cast<uint64_t>(mantissa), decimal_exponent);
+}
+
+FASTFLOAT_CONSTEXPR20 inline double
+integer_times_pow10(long long mantissa, int decimal_exponent) noexcept {
+  return integer_times_pow10(static_cast<int64_t>(mantissa), decimal_exponent);
+}
+#endif
 FASTFLOAT_CONSTEXPR20 inline double
 integer_times_pow10(unsigned mantissa, int decimal_exponent) noexcept {
   return integer_times_pow10(static_cast<uint64_t>(mantissa), decimal_exponent);
diff --git a/tests/basictest.cpp b/tests/basictest.cpp
index 4899b40..dc11752 100644
--- a/tests/basictest.cpp
+++ b/tests/basictest.cpp
@@ -2140,6 +2140,10 @@ TEST_CASE("integer_times_pow10") {
       -3141592653589793238, -18, -3.141592653589793238);
   verify_integer_multiplication_by_power_of_10<uint64_t>(
       3141592653589793238, -18, 3.141592653589793238);
+  verify_integer_multiplication_by_power_of_10<long long>(
+      -3141592653589793238, -18, -3.141592653589793238);
+  verify_integer_multiplication_by_power_of_10<unsigned long long>(
+      3141592653589793238, -18, 3.141592653589793238);
 
   for (int mode : {FE_UPWARD, FE_DOWNWARD, FE_TOWARDZERO, FE_TONEAREST}) {
     fesetround(mode);