Dear GMP developers, I've found a critical bug in gmp-6.1.2, file mpn/x86_64/invert_limb.asm, line 91: C v3 = (v2 << 31) + (v2 * (2^96 - v2 * d63 + ((v2 >> 1) & mask)) >> 65 A closing parenthesis is missing. Happy end of 2016 to all of you! Paul