diff --git a/sprout/array/hash.hpp b/sprout/array/hash.hpp
index 1f59c2db..f480e9a3 100644
--- a/sprout/array/hash.hpp
+++ b/sprout/array/hash.hpp
@@ -19,6 +19,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -26,6 +30,9 @@ namespace std {
 	struct hash<sprout::array<T, N> >
 		: public sprout::hash<sprout::array<T, N> >
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// #ifndef SPROUT_ARRAY_HASH_HPP
diff --git a/sprout/bitset/hash.hpp b/sprout/bitset/hash.hpp
index 4d923853..1913791c 100644
--- a/sprout/bitset/hash.hpp
+++ b/sprout/bitset/hash.hpp
@@ -20,6 +20,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -27,6 +31,9 @@ namespace std {
 	struct hash<sprout::bitset<N> >
 		: public sprout::hash<sprout::bitset<N> >
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// #ifndef SPROUT_BITSET_HASH_HPP
diff --git a/sprout/complex/hash.hpp b/sprout/complex/hash.hpp
index a99b80e4..f5515771 100644
--- a/sprout/complex/hash.hpp
+++ b/sprout/complex/hash.hpp
@@ -19,6 +19,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -26,6 +30,9 @@ namespace std {
 	struct hash<sprout::complex<T> >
 		: public sprout::hash<sprout::complex<T> >
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// #ifndef SPROUT_COMPLEX_HASH_HPP
diff --git a/sprout/darkroom/objects.hpp b/sprout/darkroom/objects.hpp
index 0b68c325..0695a4d5 100644
--- a/sprout/darkroom/objects.hpp
+++ b/sprout/darkroom/objects.hpp
@@ -5,5 +5,6 @@
 #include <sprout/darkroom/objects/intersect.hpp>
 #include <sprout/darkroom/objects/sphere.hpp>
 #include <sprout/darkroom/objects/aa_plane.hpp>
+#include <sprout/darkroom/objects/polygon.hpp>
 
 #endif	// #ifndef SPROUT_DARKROOM_OBJECTS_HPP
diff --git a/sprout/darkroom/objects/polygon/triangle.hpp b/sprout/darkroom/objects/polygon/triangle.hpp
index 2f6835cb..20ba296b 100644
--- a/sprout/darkroom/objects/polygon/triangle.hpp
+++ b/sprout/darkroom/objects/polygon/triangle.hpp
@@ -64,7 +64,7 @@ namespace sprout {
 							? sprout::darkroom::rays::point_of_intersection(ray, distance)
 							: position_type(0, 0, 0)
 							,
-						hit_side > 0 ? normal_ : sprout::darkroom::coords::negate(normal_),
+						normal_,//hit_side > 0 ? normal_ : sprout::darkroom::coords::negate(normal_),
 						sprout::darkroom::materials::calc_material(mat_, unit_type(0), unit_type(0))	// ???
 						);
 				}
diff --git a/sprout/logic/tribool/hash.hpp b/sprout/logic/tribool/hash.hpp
index f1a7b198..ef5ba9ba 100644
--- a/sprout/logic/tribool/hash.hpp
+++ b/sprout/logic/tribool/hash.hpp
@@ -27,6 +27,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -38,6 +42,9 @@ namespace std {
 	struct hash<sprout::logic::tribool>
 		: public sprout::hash<sprout::logic::tribool>
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// #ifndef SPROUT_LOGIC_TRIBOOL_HASH_HPP
diff --git a/sprout/math/factorial.hpp b/sprout/math/factorial.hpp
index c26aaa68..fc664e91 100644
--- a/sprout/math/factorial.hpp
+++ b/sprout/math/factorial.hpp
@@ -2,6 +2,7 @@
 #define SPROUT_MATH_FACTORIAL_HPP
 
 #include <cstddef>
+#include <cstdint>
 #include <type_traits>
 #include <sprout/config.hpp>
 #include <sprout/array/array.hpp>
diff --git a/sprout/optional/hash.hpp b/sprout/optional/hash.hpp
index cb4e08bd..af698542 100644
--- a/sprout/optional/hash.hpp
+++ b/sprout/optional/hash.hpp
@@ -21,6 +21,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -28,6 +32,9 @@ namespace std {
 	struct hash<sprout::optional<T> >
 		: public sprout::hash<sprout::optional<T> >
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// #ifndef SPROUT_OPTIONAL_HASH_HPP
diff --git a/sprout/pit/hash.hpp b/sprout/pit/hash.hpp
index 114e06e5..2d6264bf 100644
--- a/sprout/pit/hash.hpp
+++ b/sprout/pit/hash.hpp
@@ -19,6 +19,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -26,6 +30,9 @@ namespace std {
 	struct hash<sprout::pit<Container> >
 		: public sprout::hash<sprout::pit<Container> >
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// #ifndef SPROUT_PIT_HASH_HPP
diff --git a/sprout/rational/hash.hpp b/sprout/rational/hash.hpp
index 8e18e771..f79c1d14 100644
--- a/sprout/rational/hash.hpp
+++ b/sprout/rational/hash.hpp
@@ -19,6 +19,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -26,6 +30,9 @@ namespace std {
 	struct hash<sprout::rational<T> >
 		: public sprout::hash<sprout::rational<T> >
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// SPROUT_RATIONAL_HASH_HPP
diff --git a/sprout/string/hash.hpp b/sprout/string/hash.hpp
index 7d6e926d..973d6983 100644
--- a/sprout/string/hash.hpp
+++ b/sprout/string/hash.hpp
@@ -19,6 +19,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -26,6 +30,9 @@ namespace std {
 	struct hash<sprout::basic_string<T, N, Traits> >
 		: public sprout::hash<sprout::basic_string<T, N, Traits> >
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// #ifndef SPROUT_STRING_HASH_HPP
diff --git a/sprout/sub_array/hash.hpp b/sprout/sub_array/hash.hpp
index 2cf34770..3c8f4d8c 100644
--- a/sprout/sub_array/hash.hpp
+++ b/sprout/sub_array/hash.hpp
@@ -19,6 +19,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -26,6 +30,9 @@ namespace std {
 	struct hash<sprout::sub_array<Container> >
 		: public sprout::hash<sprout::sub_array<Container> >
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// #ifndef SPROUT_SUB_ARRAY_HASH_HPP
diff --git a/sprout/tuple/tuple/hash.hpp b/sprout/tuple/tuple/hash.hpp
index 4edc7bcd..00571adb 100644
--- a/sprout/tuple/tuple/hash.hpp
+++ b/sprout/tuple/tuple/hash.hpp
@@ -33,6 +33,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -40,6 +44,9 @@ namespace std {
 	struct hash<sprout::tuples::tuple<Types...> >
 		: public sprout::hash<sprout::tuples::tuple<Types...> >
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// #ifndef SPROUT_TUPLE_TUPLE_HASH_HPP
diff --git a/sprout/utility/pair/hash.hpp b/sprout/utility/pair/hash.hpp
index eab4fb23..7d3b6e79 100644
--- a/sprout/utility/pair/hash.hpp
+++ b/sprout/utility/pair/hash.hpp
@@ -19,6 +19,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -26,6 +30,9 @@ namespace std {
 	struct hash<sprout::pair<T1, T2> >
 		: public sprout::hash<sprout::pair<T1, T2> >
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// #ifndef SPROUT_UTILITY_PAIR_HASH_HPP
diff --git a/sprout/utility/string_ref/hash.hpp b/sprout/utility/string_ref/hash.hpp
index 94a262ef..3fe0bfb5 100644
--- a/sprout/utility/string_ref/hash.hpp
+++ b/sprout/utility/string_ref/hash.hpp
@@ -19,6 +19,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -26,6 +30,9 @@ namespace std {
 	struct hash<sprout::basic_string_ref<T, Traits> >
 		: public sprout::hash<sprout::basic_string_ref<T, Traits> >
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// #ifndef SPROUT_UTILITY_STRING_REF_HASH_HPP
diff --git a/sprout/utility/value_holder/hash.hpp b/sprout/utility/value_holder/hash.hpp
index 2c737e14..b9a2bf3e 100644
--- a/sprout/utility/value_holder/hash.hpp
+++ b/sprout/utility/value_holder/hash.hpp
@@ -27,6 +27,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -34,6 +38,9 @@ namespace std {
 	struct hash<sprout::value_holder<T> >
 		: public sprout::hash<sprout::value_holder<T> >
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// #ifndef SPROUT_UTILITY_VALUE_HOLDER_HASH_HPP
diff --git a/sprout/uuid/hash.hpp b/sprout/uuid/hash.hpp
index 136ae785..f1a2a9a7 100644
--- a/sprout/uuid/hash.hpp
+++ b/sprout/uuid/hash.hpp
@@ -18,6 +18,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -25,6 +29,9 @@ namespace std {
 	struct hash<sprout::uuids::uuid>
 		: public sprout::hash<sprout::uuids::uuid>
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// #ifndef SPROUT_UUID_HASH_HPP
diff --git a/sprout/variant/hash.hpp b/sprout/variant/hash.hpp
index 94ea0ca1..ff88b171 100644
--- a/sprout/variant/hash.hpp
+++ b/sprout/variant/hash.hpp
@@ -35,6 +35,10 @@ namespace sprout {
 }	// namespace sprout
 
 namespace std {
+#if defined(__clang__)
+#	pragma clang diagnostic push
+#	pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 	//
 	// hash
 	//
@@ -42,6 +46,9 @@ namespace std {
 	struct hash<sprout::variant<Types...> >
 		: public sprout::hash<sprout::variant<Types...> >
 	{};
+#if defined(__clang__)
+#	pragma clang diagnostic pop
+#endif
 }	// namespace std
 
 #endif	// #ifndef SPROUT_VARIANT_HASH_HPP