diff --git a/sprout/random/mersenne_twister.hpp b/sprout/random/mersenne_twister.hpp
index 3e00eb76..b0d714aa 100644
--- a/sprout/random/mersenne_twister.hpp
+++ b/sprout/random/mersenne_twister.hpp
@@ -249,7 +249,7 @@ namespace sprout {
 				return rewind_1(data, last, z, x_[m - 1] ^ x_[n - 1]);
 			}
 			SPROUT_CONSTEXPR bool
-			equal_impl_2(mersenne_twister_engine const& other, sprout::array<result_type, n> back, std::size_t offset, std::size_t i = 0) const {
+			equal_impl_2(mersenne_twister_engine const& other, sprout::array<result_type, n> const& back, std::size_t offset, std::size_t i = 0) const {
 				return i < offset
 					? back[i + n - offset] != other.x_[i]
 						? false
@@ -258,7 +258,7 @@ namespace sprout {
 					;
 			}
 			SPROUT_CONSTEXPR bool
-			equal_impl_1(mersenne_twister_engine const& other, sprout::array<result_type, n> back, std::size_t offset, std::size_t i = 0) const {
+			equal_impl_1(mersenne_twister_engine const& other, sprout::array<result_type, n> const& back, std::size_t offset, std::size_t i = 0) const {
 				return i + offset < n
 					? x_[i] != other.x_[i + offset]
 						? false
@@ -372,6 +372,70 @@ namespace sprout {
 			SPROUT_CONSTEXPR mersenne_twister_engine twist() const {
 				return twist_1(0);
 			}
+			SPROUT_CXX14_CONSTEXPR void do_twist() {
+				UIntType const upper_mask = (~static_cast<UIntType>(0)) << r;
+				UIntType const lower_mask = ~upper_mask;
+				std::size_t const unroll_factor = 6;
+				std::size_t const unroll_extra1 = (n - m) % unroll_factor;
+				std::size_t const unroll_extra2 = (m - 1) % unroll_factor;
+				for (std::size_t j = 0; j < n - m - unroll_extra1; ++j) {
+					UIntType y = (x_[j] & upper_mask) | (x_[j + 1] & lower_mask);
+					x_[j] = x_[j+m] ^ (y >> 1) ^ ((x_[j + 1] & 1) * a);
+				}
+				for (std::size_t j = n - m - unroll_extra1; j < n-m; ++j) {
+					UIntType y = (x_[j] & upper_mask) | (x_[j + 1] & lower_mask);
+					x_[j] = x_[j + m] ^ (y >> 1) ^ ((x_[j + 1] & 1) * a);
+				}
+				for (std::size_t j = n - m; j < n - 1 - unroll_extra2; ++j) {
+					UIntType y = (x_[j] & upper_mask) | (x_[j + 1] & lower_mask);
+					x_[j] = x_[j - (n - m)] ^ (y >> 1) ^ ((x_[j + 1] & 1) * a);
+				}
+				for (std::size_t j = n - 1 - unroll_extra2; j < n - 1; ++j) {
+					UIntType y = (x_[j] & upper_mask) | (x_[j + 1] & lower_mask);
+					x_[j] = x_[j - (n - m)] ^ (y >> 1) ^ ((x_[j + 1] & 1) * a);
+				}
+				{
+					UIntType y = (x_[n - 1] & upper_mask) | (x_[0] & lower_mask);
+					x_[n - 1] = x_[m - 1] ^ (y >> 1) ^ ((x_[0] & 1) * a);
+				}
+				i_ = 0;
+			}
+			SPROUT_CXX14_CONSTEXPR void do_rewind(UIntType* last, std::size_t z) const {
+				UIntType const upper_mask = (~static_cast<UIntType>(0)) << r;
+				UIntType const lower_mask = ~upper_mask;
+				UIntType y0 = x_[m - 1] ^ x_[n - 1];
+				if (y0 & (static_cast<UIntType>(1) << (w - 1))) {
+					y0 = ((y0 ^ a) << 1) | 1;
+				} else {
+					y0 = y0 << 1;
+				}
+				for (std::size_t sz = 0; sz < z; ++sz) {
+					UIntType y1 = rewind_find(last, sz, m - 1) ^ rewind_find(last, sz, n - 1);
+					if (y1 & (static_cast<UIntType>(1) << (w - 1))) {
+						y1 = ((y1 ^ a) << 1) | 1;
+					} else {
+						y1 = y1 << 1;
+					}
+					*(last - sz) = (y0 & upper_mask) | (y1 & lower_mask);
+					y0 = y1;
+				}
+			}
+			SPROUT_CXX14_CONSTEXPR bool do_equal_impl(mersenne_twister_engine const& other) const {
+				UIntType back[n] = {};
+				std::size_t offset = other.i_ - i_;
+				for (std::size_t j = 0; j + offset < n; ++j) {
+					if (x_[j] != other.x_[j + offset]) {
+						return false;
+					}
+				}
+				do_rewind(&back[n - 1], offset);
+				for (std::size_t j = 0; j < offset; ++j) {
+					if (back[j + n - offset] != other.x_[j]) {
+						return false;
+					}
+				}
+				return true;
+			}
 		public:
 			SPROUT_CONSTEXPR mersenne_twister_engine()
 				: x_(init_seed(default_seed))
@@ -388,12 +452,35 @@ namespace sprout {
 			SPROUT_CONSTEXPR result_type max() const SPROUT_NOEXCEPT {
 				return static_max();
 			}
+			SPROUT_CXX14_CONSTEXPR result_type operator()() {
+				if (i_ == n) {
+					do_twist();
+				}
+				UIntType z = x_[i_];
+				++i_;
+				z ^= ((z >> u) & d);
+				z ^= ((z << s) & b);
+				z ^= ((z << t) & c);
+				z ^= (z >> l);
+				return z;
+			}
 			SPROUT_CONSTEXPR sprout::random::random_result<mersenne_twister_engine> const operator()() const {
 				return i_ == n
 					? twist().generate()
 					: generate()
 					;
 			}
+#ifndef SPROUT_CONFIG_DISABLE_CXX14_CONSTEXPR
+			friend SPROUT_CXX14_CONSTEXPR bool operator==(mersenne_twister_engine const& lhs, mersenne_twister_engine const& rhs) SPROUT_NOEXCEPT {
+				return lhs.i_ < rhs.i_
+					? lhs.do_equal_impl(rhs)
+					: rhs.do_equal_impl(lhs)
+					;
+			}
+			friend SPROUT_CXX14_CONSTEXPR bool operator!=(mersenne_twister_engine const& lhs, mersenne_twister_engine const& rhs) SPROUT_NOEXCEPT {
+				return !(lhs == rhs);
+			}
+#else	// #ifndef SPROUT_CONFIG_DISABLE_CXX14_CONSTEXPR
 			friend SPROUT_CONSTEXPR bool operator==(mersenne_twister_engine const& lhs, mersenne_twister_engine const& rhs) SPROUT_NOEXCEPT {
 				return lhs.i_ < rhs.i_
 					? lhs.equal_impl(rhs)
@@ -403,6 +490,7 @@ namespace sprout {
 			friend SPROUT_CONSTEXPR bool operator!=(mersenne_twister_engine const& lhs, mersenne_twister_engine const& rhs) SPROUT_NOEXCEPT {
 				return !(lhs == rhs);
 			}
+#endif	// #ifndef SPROUT_CONFIG_DISABLE_CXX14_CONSTEXPR
 			template<typename Elem, typename Traits>
 			friend SPROUT_NON_CONSTEXPR std::basic_istream<Elem, Traits>& operator>>(
 				std::basic_istream<Elem, Traits>& lhs,