diff --git a/libs/algorithm/test/generate.cpp b/libs/algorithm/test/generate.cpp
index 9ecbd2ca..3a816f74 100644
--- a/libs/algorithm/test/generate.cpp
+++ b/libs/algorithm/test/generate.cpp
@@ -11,7 +11,7 @@ namespace testspr {
 	static void algorithm_generate_test() {
 		using namespace sprout;
 		{
-			SPROUT_STATIC_CONSTEXPR auto arr1 = array<int, 10>{{0}};
+			SPROUT_STATIC_CONSTEXPR auto arr1 = array<int, 10>{{}};
 
 			// ����
 			{
diff --git a/libs/algorithm/test/generate_n.cpp b/libs/algorithm/test/generate_n.cpp
index 9d8af43a..158136fb 100644
--- a/libs/algorithm/test/generate_n.cpp
+++ b/libs/algorithm/test/generate_n.cpp
@@ -11,7 +11,7 @@ namespace testspr {
 	static void algorithm_generate_n_test() {
 		using namespace sprout;
 		{
-			SPROUT_STATIC_CONSTEXPR auto arr1 = array<int, 10>{{0}};
+			SPROUT_STATIC_CONSTEXPR auto arr1 = array<int, 10>{{}};
 
 			// ����
 			{
diff --git a/sprout/iterator/filter_iterator.hpp b/sprout/iterator/filter_iterator.hpp
index b801261f..321f8fb7 100644
--- a/sprout/iterator/filter_iterator.hpp
+++ b/sprout/iterator/filter_iterator.hpp
@@ -55,13 +55,13 @@ namespace sprout {
 		iterator_type last;
 		predicate_type pred;
 	private:
-		iterator_type satisfy_predicate() {
-			while (current != last && !pred(current)) {
+		void satisfy_predicate() {
+			while (current != last && !pred(*current)) {
 				++current;
 			}
 		}
-		iterator_type satisfy_predicate_backward() {
-			while (!pred(current)) {
+		void satisfy_predicate_backward() {
+			while (!pred(*current)) {
 				--current;
 			}
 		}
diff --git a/sprout/range/adaptor/replaced.hpp b/sprout/range/adaptor/replaced.hpp
index 4faca60b..e847c3bb 100644
--- a/sprout/range/adaptor/replaced.hpp
+++ b/sprout/range/adaptor/replaced.hpp
@@ -29,7 +29,7 @@ namespace sprout {
 					: old_(old_value)
 					, new_(new_value)
 				{}
-				T const& operator()(T const& value) const {
+				SPROUT_CONSTEXPR T const& operator()(T const& value) const {
 					return (value == old_) ? new_ : value;
 				}
 			};
diff --git a/sprout/range/adaptor/replaced_if.hpp b/sprout/range/adaptor/replaced_if.hpp
index 1ae8ac95..38901f6a 100644
--- a/sprout/range/adaptor/replaced_if.hpp
+++ b/sprout/range/adaptor/replaced_if.hpp
@@ -30,8 +30,8 @@ namespace sprout {
 					: pred_(pred)
 					, new_(new_value)
 				{}
-				T const& operator()(T const& value) const {
-					return pred(value) ? new_ : value;
+				SPROUT_CONSTEXPR T const& operator()(T const& value) const {
+					return pred_(value) ? new_ : value;
 				}
 			};
 		}	// namespace detail
diff --git a/testspr/tools.hpp b/testspr/tools.hpp
index 6e073351..d75a01f3 100644
--- a/testspr/tools.hpp
+++ b/testspr/tools.hpp
@@ -67,6 +67,18 @@ namespace testspr {
 	public:
 		SPROUT_CONSTEXPR bool operator()(T const& t) const { return t % 2 != 0; }
 	};
+	//
+	// is_multiple_of
+	//
+	template<typename T, typename U = T>
+	struct is_multiple_of {
+	public:
+		typedef T first_argument_type;
+		typedef U second_argument_type;
+		typedef bool result_type;
+	public:
+		SPROUT_CONSTEXPR bool operator()(T const& t, U const& u) const { return t % u == 0; }
+	};
 
 	//
 	// less