diff --git a/js/src/ctypes/CTypes.cpp b/js/src/ctypes/CTypes.cpp

index 763d6e6..8b04fc8 100644

--- a/js/src/ctypes/CTypes.cpp

+++ b/js/src/ctypes/CTypes.cpp

@@ -1023,6 +1023,19 @@ static JS_ALWAYS_INLINE TargetType Convert(FromType d)

return ConvertImpl<TargetType, FromType>::Convert(d);

}

+template<class Type>

+class no_bug_numeric_digits

+{

+ public:

+ static const int digits = numeric_limits<Type>::digits;

+};

+template<>

+class no_bug_numeric_digits<unsigned long long>

+{

+ public:

+ static const int digits = 64;

+};

+

template<class TargetType, class FromType>

static JS_ALWAYS_INLINE bool IsAlwaysExact()

{

@@ -1035,7 +1048,7 @@ static JS_ALWAYS_INLINE bool IsAlwaysExact()

// 2) If FromType is signed, TargetType must also be signed. (Floating point

// types are always signed.)

// 3) If TargetType is an exact integral type, FromType must be also.

- if (numeric_limits<TargetType>::digits < numeric_limits<FromType>::digits)

+ if (numeric_limits<TargetType>::digits < no_bug_numeric_digits<FromType>::digits)

return false;

if (numeric_limits<FromType>::is_signed &&