diff --git a/sprout/algorithm/cxx14.hpp b/sprout/algorithm/cxx14.hpp
index 9953d372..467fdd15 100644
--- a/sprout/algorithm/cxx14.hpp
+++ b/sprout/algorithm/cxx14.hpp
@@ -46,8 +46,8 @@
 #include <sprout/algorithm/cxx14/partial_sort.hpp>
 #include <sprout/algorithm/cxx14/partial_sort_copy.hpp>
 #include <sprout/algorithm/cxx14/nth_element.hpp>
-//#include <sprout/algorithm/cxx14/merge.hpp>
-//#include <sprout/algorithm/cxx14/inplace_merge.hpp>
+#include <sprout/algorithm/cxx14/merge.hpp>
+#include <sprout/algorithm/cxx14/inplace_merge.hpp>
 //#include <sprout/algorithm/cxx14/set_union.hpp>
 //#include <sprout/algorithm/cxx14/set_intersection.hpp>
 //#include <sprout/algorithm/cxx14/set_difference.hpp>
diff --git a/sprout/algorithm/cxx14/inplace_merge.hpp b/sprout/algorithm/cxx14/inplace_merge.hpp
new file mode 100644
index 00000000..b6940625
--- /dev/null
+++ b/sprout/algorithm/cxx14/inplace_merge.hpp
@@ -0,0 +1,27 @@
+/*=============================================================================
+  Copyright (c) 2011-2014 Bolero MURAKAMI
+  https://github.com/bolero-MURAKAMI/Sprout
+
+  Distributed under the Boost Software License, Version 1.0. (See accompanying
+  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+=============================================================================*/
+#ifndef SPROUT_ALGORITHM_CXX14_INPLACE_MERGE_HPP
+#define SPROUT_ALGORITHM_CXX14_INPLACE_MERGE_HPP
+
+#include <sprout/config.hpp>
+
+namespace sprout {
+	//
+	// 25.4.4 Merge
+	//
+	// !!! TODO: implementation
+	template<typename BidirectionalIterator>
+	inline SPROUT_CXX14_CONSTEXPR void
+	inplace_merge(BidirectionalIterator first, BidirectionalIterator middle, BidirectionalIterator last);
+
+	template<typename BidirectionalIterator, typename Compare>
+	inline SPROUT_CXX14_CONSTEXPR void
+	inplace_merge(BidirectionalIterator first, BidirectionalIterator middle, BidirectionalIterator last, Compare comp);
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_ALGORITHM_CXX14_INPLACE_MERGE_HPP
diff --git a/sprout/algorithm/cxx14/merge.hpp b/sprout/algorithm/cxx14/merge.hpp
new file mode 100644
index 00000000..79e66e76
--- /dev/null
+++ b/sprout/algorithm/cxx14/merge.hpp
@@ -0,0 +1,54 @@
+/*=============================================================================
+  Copyright (c) 2011-2014 Bolero MURAKAMI
+  https://github.com/bolero-MURAKAMI/Sprout
+
+  Distributed under the Boost Software License, Version 1.0. (See accompanying
+  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+=============================================================================*/
+#ifndef SPROUT_ALGORITHM_CXX14_MERGE_HPP
+#define SPROUT_ALGORITHM_CXX14_MERGE_HPP
+
+#include <sprout/config.hpp>
+#include <sprout/iterator/type_traits/is_iterator_of.hpp>
+#include <sprout/type_traits/enabler_if.hpp>
+#include <sprout/algorithm/cxx14/copy.hpp>
+#include <sprout/functional/less.hpp>
+
+namespace sprout {
+	//
+	// 25.4.4 Merge
+	//
+	template<
+		typename InputIterator1, typename InputIterator2, typename OutputIterator, typename Compare,
+		typename sprout::enabler_if<sprout::is_iterator_outputable<OutputIterator>::value>::type = sprout::enabler
+	>
+	inline SPROUT_CXX14_CONSTEXPR OutputIterator
+	merge(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp) {
+		while (true) {
+			if (first1 == last1) {
+				return std::copy(first2, last2, result);
+			}
+			if (first2 == last2) {
+				return std::copy(first1, last1, result);
+			}
+			*result++ = comp(*first2, *first1)
+				? *first2++
+				: *first1++
+				;
+		}
+	}
+
+	template<
+		typename InputIterator1, typename InputIterator2, typename OutputIterator,
+		typename sprout::enabler_if<sprout::is_iterator_outputable<OutputIterator>::value>::type = sprout::enabler
+	>
+	inline SPROUT_CXX14_CONSTEXPR OutputIterator
+	merge(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, OutputIterator result) {
+		return sprout::merge(
+			first1, last1, first2, last2, result,
+			sprout::less<>()
+			);
+	}
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_ALGORITHM_CXX14_MERGE_HPP
diff --git a/sprout/tuple/tuple/type_traits.hpp b/sprout/tuple/tuple/type_traits.hpp
index 0fe62744..bc4640f8 100644
--- a/sprout/tuple/tuple/type_traits.hpp
+++ b/sprout/tuple/tuple/type_traits.hpp
@@ -40,7 +40,7 @@ namespace sprout {
 #if SPROUT_USE_VARIABLE_TEMPLATES
 	namespace tuples {
 		template<typename T>
-		SPROUT_STATIC_CONSTEXPR bool is_tuple_v = sprout::tuples::is_tuple_v<T>::value;
+		SPROUT_STATIC_CONSTEXPR bool is_tuple_v = sprout::tuples::is_tuple<T>::value;
 	}	// namespace tuples
 
 	using sprout::tuples::is_tuple;