diff --git a/include/sqlpp11/detail/basic_operators.h b/include/sqlpp11/detail/basic_operators.h
index 02a2a3ae..a534cb00 100644
--- a/include/sqlpp11/detail/basic_operators.h
+++ b/include/sqlpp11/detail/basic_operators.h
@@ -127,12 +127,12 @@ namespace sqlpp
 					return { *static_cast<const Base*>(this), std::forward<T>(t) };
 				}
 
-			nary_expression_t<Base, is_null_> is_null() const
+			null_expression_t<Base, is_null_> is_null() const
 			{
 				return { *static_cast<const Base*>(this) };
 			}
 
-			nary_expression_t<Base, is_not_null_> is_not_null() const
+			null_expression_t<Base, is_not_null_> is_not_null() const
 			{
 				return { *static_cast<const Base*>(this) };
 			}
@@ -147,7 +147,7 @@ namespace sqlpp
 				return { *static_cast<const Base*>(this) };
 			}
 
-			// Hint: use wrappers for containers...
+			// Hint: use value_list wrapper for containers...
 			template<typename... T>
 				nary_expression_t<Base, in_, typename Constraint<T>::type...> in(T&&... t) const
 				{
diff --git a/include/sqlpp11/expression.h b/include/sqlpp11/expression.h
index 7e2e947d..844d70fb 100644
--- a/include/sqlpp11/expression.h
+++ b/include/sqlpp11/expression.h
@@ -172,6 +172,38 @@ namespace sqlpp
 			Lhs _lhs;
 		};
 
+	template<typename Lhs, typename O>
+		struct null_expression_t: public O::_value_type::template operators<null_expression_t<Lhs, O>>
+		{
+			using _value_type = typename O::_value_type;
+
+			null_expression_t(Lhs&& l):
+				_lhs(std::move(l))
+			{}
+
+			null_expression_t(const Lhs& l):
+				_lhs(l)
+			{}
+
+			null_expression_t(const null_expression_t&) = default;
+			null_expression_t(null_expression_t&&) = default;
+			null_expression_t& operator=(const null_expression_t&) = default;
+			null_expression_t& operator=(null_expression_t&&) = default;
+			~null_expression_t() = default;
+
+			template<typename Db>
+				void serialize(std::ostream& os, Db& db) const
+				{
+					os << "(";
+					_lhs.serialize(os, db);
+					os << ")";
+					os << O::_name;
+				}
+
+		private:
+			Lhs _lhs;
+		};
+
 	template<typename Lhs, typename O, typename... Rhs>
 		struct nary_expression_t: public O::_value_type::template operators<nary_expression_t<Lhs, O, Rhs...>>
 		{