diff --git a/include/sqlpp11/basic_expression_operators.h b/include/sqlpp11/basic_expression_operators.h
index b3e74d86..9e97a044 100644
--- a/include/sqlpp11/basic_expression_operators.h
+++ b/include/sqlpp11/basic_expression_operators.h
@@ -134,14 +134,14 @@ namespace sqlpp
 			template<typename... T>
 				vendor::in_t<true, Base, vendor::wrap_operand_t<T>...> in(T... t) const
 				{
-					static_assert(detail::all_t<_is_valid_comparison_operand, vendor::wrap_operand_t<T>...>::value, "at least one operand of in() is not valid");
+					static_assert(detail::all_t<_is_valid_comparison_operand<vendor::wrap_operand_t<T>>::value...>::value, "at least one operand of in() is not valid");
 					return { *static_cast<const Base*>(this), vendor::wrap_operand_t<T>{t}... };
 				}
 
 			template<typename... T>
 				vendor::in_t<false, Base, vendor::wrap_operand_t<T>...> not_in(T... t) const
 				{
-					static_assert(detail::all_t<_is_valid_comparison_operand, vendor::wrap_operand_t<T>...>::value, "at least one operand of in() is not valid");
+					static_assert(detail::all_t<_is_valid_comparison_operand<vendor::wrap_operand_t<T>>::value...>::value, "at least one operand of in() is not valid");
 					return { *static_cast<const Base*>(this), vendor::wrap_operand_t<T>{t}... };
 				}
 
diff --git a/include/sqlpp11/detail/logic.h b/include/sqlpp11/detail/logic.h
index 14527010..4f1dfb29 100644
--- a/include/sqlpp11/detail/logic.h
+++ b/include/sqlpp11/detail/logic.h
@@ -36,10 +36,10 @@ namespace sqlpp
 		template<bool... B>
 			struct logic_helper;
 
-		template<template<typename> class Predicate, typename... T>
+		template<bool... B>
 			using all_t = std::integral_constant<
 						bool,
-						std::is_same<logic_helper<Predicate<T>::value...>, logic_helper<(true or Predicate<T>::value)...>>::value>;
+						std::is_same<logic_helper<B...>, logic_helper<(true or B)...>>::value>;
 
 		template<bool... B>
 			using any_t = std::integral_constant<
diff --git a/include/sqlpp11/detail/type_set.h b/include/sqlpp11/detail/type_set.h
index 63cef7d6..6aadd0b7 100644
--- a/include/sqlpp11/detail/type_set.h
+++ b/include/sqlpp11/detail/type_set.h
@@ -82,26 +82,6 @@ namespace sqlpp
 				static constexpr bool value = any_t<std::is_same<E, Elements>::value...>::value;
 			};
 
-		template<typename L, typename R>
-			struct is_superset_of
-			{
-				static_assert(::sqlpp::vendor::wrong_t<L, R>::value, "L and R have to be type sets");
-			};
-
-		template<typename... LElements, typename... RElements>
-			struct is_superset_of<type_set<LElements...>, type_set<RElements...>>
-			{
-				template<typename X>
-					using is_element_of_L = is_element_of<X, type_set<LElements...>>;
-				static constexpr bool value = all_t<is_element_of_L, RElements...>::value;
-			};
-
-		template<typename L, typename R>
-			struct is_subset_of
-			{
-				static constexpr bool value = is_superset_of<R, L>::value;
-			};
-
 		template<typename L, typename R>
 			struct joined_set
 			{
@@ -117,6 +97,24 @@ namespace sqlpp
 		template<typename L, typename R>
 			using joined_set_t = typename joined_set<L, R>::type;
 
+		template<typename L, typename R>
+			struct is_superset_of
+			{
+				static_assert(::sqlpp::vendor::wrong_t<L, R>::value, "L and R have to be type sets");
+			};
+
+		template<typename... LElements, typename... RElements>
+			struct is_superset_of<type_set<LElements...>, type_set<RElements...>>
+			{
+				static constexpr bool value = joined_set_t<type_set<LElements...>, type_set<RElements...>>::size::value == sizeof...(LElements);
+			};
+
+		template<typename L, typename R>
+			struct is_subset_of
+			{
+				static constexpr bool value = is_superset_of<R, L>::value;
+			};
+
 		template<typename L, typename R>
 			struct is_disjunct_from
 			{
diff --git a/include/sqlpp11/multi_column.h b/include/sqlpp11/multi_column.h
index 821cd1c2..89fdc464 100644
--- a/include/sqlpp11/multi_column.h
+++ b/include/sqlpp11/multi_column.h
@@ -41,7 +41,7 @@ namespace sqlpp
 	template<typename Unused, typename... Columns>
 		struct multi_column_t
 		{
-			static_assert(detail::all_t<is_named_expression_t, Columns...>::value, "multi_column parameters need to be named expressions");
+			static_assert(detail::all_t<is_named_expression_t<Columns>::value...>::value, "multi_column parameters need to be named expressions");
 
 			using _table_set = sqlpp::detail::make_joined_set_t<typename Columns::_table_set...>;
 
@@ -75,7 +75,7 @@ namespace sqlpp
 	template<typename AliasProvider, typename... Columns>
 		struct multi_column_alias_t
 		{
-			static_assert(detail::all_t<is_named_expression_t, Columns...>::value, "multi_column parameters need to be named expressions");
+			static_assert(detail::all_t<is_named_expression_t<Columns>::value...>::value, "multi_column parameters need to be named expressions");
 
 			using _name_t = typename AliasProvider::_name_t;
 			using _table_set = sqlpp::detail::make_joined_set_t<typename Columns::_table_set...>;
diff --git a/include/sqlpp11/on.h b/include/sqlpp11/on.h
index da874957..25fc7e94 100644
--- a/include/sqlpp11/on.h
+++ b/include/sqlpp11/on.h
@@ -41,7 +41,7 @@ namespace sqlpp
 			using _is_dynamic = typename std::conditional<std::is_same<Database, void>::value, std::false_type, std::true_type>::type;
 
 			static_assert(_is_dynamic::value or sizeof...(Expr), "at least one expression argument required in on()");
-			static_assert(detail::all_t<is_expression_t, Expr...>::value, "at least one argument is not an expression in on()");
+			static_assert(detail::all_t<is_expression_t<Expr>::value...>::value, "at least one argument is not an expression in on()");
 
 			template<typename E>
 				void add(E expr)
diff --git a/include/sqlpp11/vendor/concat.h b/include/sqlpp11/vendor/concat.h
index c88aae93..332c17fc 100644
--- a/include/sqlpp11/vendor/concat.h
+++ b/include/sqlpp11/vendor/concat.h
@@ -39,7 +39,7 @@ namespace sqlpp
 			struct concat_t: public First::_value_type::template expression_operators<concat_t<First, Args...>>
 		{
 			static_assert(sizeof...(Args) > 0, "concat requires two arguments at least");
-			static_assert(sqlpp::detail::all_t<is_text_t, First, Args...>::value, "at least one non-text argument detected in concat()");
+			static_assert(sqlpp::detail::all_t<is_text_t<First>::value, is_text_t<Args>::value...>::value, "at least one non-text argument detected in concat()");
 			using _table_set = typename ::sqlpp::detail::make_joined_set<typename First::_table_set, typename Args::_table_set...>::type;
 
 			struct _value_type: public First::_value_type::_base_value_type
diff --git a/include/sqlpp11/vendor/extra_tables.h b/include/sqlpp11/vendor/extra_tables.h
index 0b91ad7a..c9fceb77 100644
--- a/include/sqlpp11/vendor/extra_tables.h
+++ b/include/sqlpp11/vendor/extra_tables.h
@@ -45,7 +45,7 @@ namespace sqlpp
 
 				static_assert(not ::sqlpp::detail::has_duplicates<Tables...>::value, "at least one duplicate argument detected in extra_tables()");
 
-				static_assert(::sqlpp::detail::all_t<is_table_t, Tables...>::value, "at least one argument is not a table or join in extra_tables()");
+				static_assert(::sqlpp::detail::all_t<is_table_t<Tables>::value...>::value, "at least one argument is not a table or join in extra_tables()");
 
 				using _table_set = ::sqlpp::detail::make_joined_set_t<typename Tables::_table_set...>;
 
diff --git a/include/sqlpp11/vendor/from.h b/include/sqlpp11/vendor/from.h
index 6949cfee..ca9c1d8f 100644
--- a/include/sqlpp11/vendor/from.h
+++ b/include/sqlpp11/vendor/from.h
@@ -49,7 +49,7 @@ namespace sqlpp
 				// FIXME: Joins contain two tables. This is not being dealt with at the moment when looking at duplicates, for instance
 				static_assert(not ::sqlpp::detail::has_duplicates<Tables...>::value, "at least one duplicate argument detected in from()");
 
-				static_assert(::sqlpp::detail::all_t<is_table_t, Tables...>::value, "at least one argument is not a table or join in from()");
+				static_assert(::sqlpp::detail::all_t<is_table_t<Tables>::value...>::value, "at least one argument is not a table or join in from()");
 
 				using _table_set = ::sqlpp::detail::make_joined_set_t<typename Tables::_table_set...>;
 
@@ -73,7 +73,7 @@ namespace sqlpp
 								static_assert(_is_dynamic::value, "add_from must not be called for static from()");
 								static_assert(is_table_t<Table>::value, "invalid table argument in add_from()");
 
-								using ok = ::sqlpp::detail::all_t<sqlpp::detail::identity_t, _is_dynamic, is_table_t<Table>>;
+								using ok = ::sqlpp::detail::all_t<_is_dynamic::value, is_table_t<Table>::value>;
 
 								_add_from_impl(table, ok()); // dispatch to prevent compile messages after the static_assert
 							}
diff --git a/include/sqlpp11/vendor/group_by.h b/include/sqlpp11/vendor/group_by.h
index 6d3dfba1..3bbc7049 100644
--- a/include/sqlpp11/vendor/group_by.h
+++ b/include/sqlpp11/vendor/group_by.h
@@ -54,7 +54,7 @@ namespace sqlpp
 
 				static_assert(not ::sqlpp::detail::has_duplicates<Expressions...>::value, "at least one duplicate argument detected in group_by()");
 
-				static_assert(::sqlpp::detail::all_t<is_expression_t, Expressions...>::value, "at least one argument is not an expression in group_by()");
+				static_assert(::sqlpp::detail::all_t<is_expression_t<Expressions>::value...>::value, "at least one argument is not an expression in group_by()");
 
 				group_by_t(Expressions... expressions):
 					_expressions(expressions...)
@@ -82,7 +82,7 @@ namespace sqlpp
 								static_assert(is_expression_t<Expression>::value, "invalid expression argument in add_group_by()");
 								static_assert(TableCheckRequired::value or Policies::template _no_unknown_tables<Expression>::value, "expression uses tables unknown to this statement in add_group_by()");
 
-								using ok = ::sqlpp::detail::all_t<sqlpp::detail::identity_t, _is_dynamic, is_expression_t<Expression>>;
+								using ok = ::sqlpp::detail::all_t<_is_dynamic::value, is_expression_t<Expression>::value>;
 
 								_add_group_by_impl(expression, ok()); // dispatch to prevent compile messages after the static_assert
 							}
diff --git a/include/sqlpp11/vendor/having.h b/include/sqlpp11/vendor/having.h
index 20beeb97..51447187 100644
--- a/include/sqlpp11/vendor/having.h
+++ b/include/sqlpp11/vendor/having.h
@@ -47,7 +47,7 @@ namespace sqlpp
 				using _parameter_tuple_t = std::tuple<Expressions...>;
 
 				static_assert(_is_dynamic::value or sizeof...(Expressions), "at least one expression argument required in having()");
-				static_assert(::sqlpp::detail::all_t<is_expression_t, Expressions...>::value, "at least one argument is not an expression in having()");
+				static_assert(::sqlpp::detail::all_t<is_expression_t<Expressions>::value...>::value, "at least one argument is not an expression in having()");
 
 				using _parameter_list_t = typename make_parameter_list_t<_parameter_tuple_t>::type;
 
@@ -79,7 +79,7 @@ namespace sqlpp
 								static_assert(is_expression_t<Expression>::value, "invalid expression argument in add_having()");
 								static_assert(TableCheckRequired::value or Policies::template _no_unknown_tables<Expression>::value, "expression uses tables unknown to this statement in add_having()");
 
-								using ok = ::sqlpp::detail::all_t<sqlpp::detail::identity_t, _is_dynamic, is_expression_t<Expression>>;
+								using ok = ::sqlpp::detail::all_t<_is_dynamic::value, is_expression_t<Expression>::value>;
 
 								_add_having_impl(expression, ok()); // dispatch to prevent compile messages after the static_assert
 							}
diff --git a/include/sqlpp11/vendor/insert_value_list.h b/include/sqlpp11/vendor/insert_value_list.h
index 5bc38c66..8b70f9db 100644
--- a/include/sqlpp11/vendor/insert_value_list.h
+++ b/include/sqlpp11/vendor/insert_value_list.h
@@ -65,7 +65,7 @@ namespace sqlpp
 
 				static_assert(not ::sqlpp::detail::has_duplicates<Assignments...>::value, "at least one duplicate argument detected in set()");
 
-				static_assert(sqlpp::detail::all_t<is_assignment_t, Assignments...>::value, "at least one argument is not an assignment in set()");
+				static_assert(sqlpp::detail::all_t<is_assignment_t<Assignments>::value...>::value, "at least one argument is not an assignment in set()");
 
 					static_assert(sqlpp::detail::none_t<must_not_insert_t<typename Assignments::_column_t>::value...>::value, "at least one assignment is prohibited by its column definition in set()");
 
@@ -101,12 +101,12 @@ namespace sqlpp
 								static_assert(::sqlpp::detail::is_subset_of<_value_table_set, typename Policies::_table_set>::value, "add_set() contains a column from a foreign table");
 								static_assert(::sqlpp::detail::is_subset_of<_column_table_set, typename Policies::_table_set>::value, "add_set() contains a value from a foreign table");
 
-								using ok = ::sqlpp::detail::all_t<sqlpp::detail::identity_t, 
-											_is_dynamic, 
-											is_assignment_t<Assignment>, 
-											::sqlpp::detail::not_t<must_not_insert_t, typename Assignment::_column_t>,
-											::sqlpp::detail::is_subset_of<_value_table_set, typename Policies::_table_set>,
-											::sqlpp::detail::is_subset_of<_column_table_set, typename Policies::_table_set>>;
+								using ok = ::sqlpp::detail::all_t<
+											_is_dynamic::value, 
+											is_assignment_t<Assignment>::value, 
+											not must_not_insert_t<typename Assignment::_column_t>::value,
+											::sqlpp::detail::is_subset_of<_value_table_set, typename Policies::_table_set>::value,
+											::sqlpp::detail::is_subset_of<_column_table_set, typename Policies::_table_set>::value>;
 
 								_add_set_impl(assignment, ok()); // dispatch to prevent compile messages after the static_assert
 							}
@@ -142,7 +142,7 @@ namespace sqlpp
 
 				static_assert(not ::sqlpp::detail::has_duplicates<Columns...>::value, "at least one duplicate argument detected in columns()");
 
-				static_assert(::sqlpp::detail::all_t<is_column_t, Columns...>::value, "at least one argument is not a column in columns()");
+				static_assert(::sqlpp::detail::all_t<is_column_t<Columns>::value...>::value, "at least one argument is not a column in columns()");
 
 				static_assert(::sqlpp::detail::none_t<must_not_insert_t<Columns>::value...>::value, "at least one column argument has a must_not_insert flag in its definition");
 
@@ -167,14 +167,14 @@ namespace sqlpp
 						template<typename... Assignments>
 							void add_values(Assignments... assignments)
 							{
-								static_assert(::sqlpp::detail::all_t<is_assignment_t, Assignments...>::value, "add_values() arguments have to be assignments");
+								static_assert(::sqlpp::detail::all_t<is_assignment_t<Assignments>::value...>::value, "add_values() arguments have to be assignments");
 								using _arg_value_tuple = std::tuple<vendor::insert_value_t<typename Assignments::_column_t>...>;
 								using _args_correct = std::is_same<_arg_value_tuple, _value_tuple_t>;
 								static_assert(_args_correct::value, "add_values() arguments do not match columns() arguments");
 
-								using ok = ::sqlpp::detail::all_t<sqlpp::detail::identity_t, 
-											::sqlpp::detail::all_t<is_assignment_t, Assignments...>, 
-											_args_correct>;
+								using ok = ::sqlpp::detail::all_t<
+											::sqlpp::detail::all_t<is_assignment_t<Assignments>::value...>::value, 
+											_args_correct::value>;
 
 								_add_values_impl(ok(), assignments...); // dispatch to prevent compile messages after the static_assert
 							}
diff --git a/include/sqlpp11/vendor/order_by.h b/include/sqlpp11/vendor/order_by.h
index 9eae6c43..724239b0 100644
--- a/include/sqlpp11/vendor/order_by.h
+++ b/include/sqlpp11/vendor/order_by.h
@@ -53,7 +53,7 @@ namespace sqlpp
 
 				static_assert(not ::sqlpp::detail::has_duplicates<Expressions...>::value, "at least one duplicate argument detected in order_by()");
 
-				static_assert(::sqlpp::detail::all_t<is_sort_order_t, Expressions...>::value, "at least one argument is not a sort order expression in order_by()");
+				static_assert(::sqlpp::detail::all_t<is_sort_order_t<Expressions>::value...>::value, "at least one argument is not a sort order expression in order_by()");
 
 				order_by_t(Expressions... expressions):
 					_expressions(expressions...)
@@ -81,7 +81,7 @@ namespace sqlpp
 								static_assert(is_sort_order_t<Expression>::value, "invalid expression argument in add_order_by()");
 								static_assert(TableCheckRequired::value or Policies::template _no_unknown_tables<Expression>::value, "expression uses tables unknown to this statement in add_order_by()");
 
-								using ok = ::sqlpp::detail::all_t<sqlpp::detail::identity_t, _is_dynamic, is_sort_order_t<Expression>>;
+								using ok = ::sqlpp::detail::all_t<_is_dynamic::value, is_sort_order_t<Expression>::value>;
 
 								_add_order_by_impl(expression, ok()); // dispatch to prevent compile messages after the static_assert
 							}
diff --git a/include/sqlpp11/vendor/select_column_list.h b/include/sqlpp11/vendor/select_column_list.h
index 52a48045..5c06710f 100644
--- a/include/sqlpp11/vendor/select_column_list.h
+++ b/include/sqlpp11/vendor/select_column_list.h
@@ -143,7 +143,7 @@ namespace sqlpp
 
 				template<typename T>
 					using is_valid_expression_t = std::integral_constant<bool, is_named_expression_t<T>::value or is_multi_column_t<T>::value>;
-				static_assert(::sqlpp::detail::all_t<is_valid_expression_t, Columns...>::value, "at least one argument is not a named expression");
+				static_assert(::sqlpp::detail::all_t<is_valid_expression_t<Columns>::value...>::value, "at least one argument is not a named expression");
 
 				static_assert(not ::sqlpp::detail::has_duplicates<typename Columns::_name_t...>::value, "at least one duplicate name detected");
 
@@ -206,9 +206,9 @@ namespace sqlpp
 								using column_names = ::sqlpp::detail::make_type_set_t<typename Columns::_name_t...>;
 								static_assert(not ::sqlpp::detail::is_element_of<typename NamedExpression::_name_t, column_names>::value, "a column of this name is present in the select already");
 
-								using ok = ::sqlpp::detail::all_t<sqlpp::detail::identity_t, 
-											_is_dynamic, 
-											is_named_expression_t<NamedExpression>
+								using ok = ::sqlpp::detail::all_t<
+											_is_dynamic::value, 
+											is_named_expression_t<NamedExpression>::value
 												>;
 
 								_add_column_impl(namedExpression, ok()); // dispatch to prevent compile messages after the static_assert
diff --git a/include/sqlpp11/vendor/select_flag_list.h b/include/sqlpp11/vendor/select_flag_list.h
index 93384318..a5e9036b 100644
--- a/include/sqlpp11/vendor/select_flag_list.h
+++ b/include/sqlpp11/vendor/select_flag_list.h
@@ -50,7 +50,7 @@ namespace sqlpp
 
 				static_assert(not ::sqlpp::detail::has_duplicates<Flags...>::value, "at least one duplicate argument detected in select flag list");
 
-				static_assert(::sqlpp::detail::all_t<is_select_flag_t, Flags...>::value, "at least one argument is not a select flag in select flag list");
+				static_assert(::sqlpp::detail::all_t<is_select_flag_t<Flags>::value...>::value, "at least one argument is not a select flag in select flag list");
 
 				select_flag_list_t(Flags... flags):
 					_flags(flags...)
@@ -78,7 +78,7 @@ namespace sqlpp
 								static_assert(is_select_flag_t<Flag>::value, "invalid select flag argument in add_flag()");
 								static_assert(TableCheckRequired::value or Policies::template _no_unknown_tables<Flag>::value, "flag uses tables unknown to this statement in add_flag()");
 
-								using ok = ::sqlpp::detail::all_t<sqlpp::detail::identity_t, _is_dynamic, is_select_flag_t<Flag>>;
+								using ok = ::sqlpp::detail::all_t<_is_dynamic::value, is_select_flag_t<Flag>::value>;
 
 								_add_flag_impl(flag, ok()); // dispatch to prevent compile messages after the static_assert
 							}
diff --git a/include/sqlpp11/vendor/update_list.h b/include/sqlpp11/vendor/update_list.h
index c3539629..9b0c808c 100644
--- a/include/sqlpp11/vendor/update_list.h
+++ b/include/sqlpp11/vendor/update_list.h
@@ -48,7 +48,7 @@ namespace sqlpp
 
 				static_assert(not ::sqlpp::detail::has_duplicates<Assignments...>::value, "at least one duplicate argument detected in set()");
 
-				static_assert(::sqlpp::detail::all_t<is_assignment_t, Assignments...>::value, "at least one argument is not an assignment in set()");
+				static_assert(::sqlpp::detail::all_t<is_assignment_t<Assignments>::value...>::value, "at least one argument is not an assignment in set()");
 
 				static_assert(::sqlpp::detail::none_t<must_not_update_t<typename Assignments::_column_t>::value...>::value, "at least one assignment is prohibited by its column definition in set()");
 
@@ -85,10 +85,10 @@ namespace sqlpp
 								static_assert(sqlpp::detail::not_t<must_not_update_t, typename Assignment::_column_t>::value, "add_set() argument must not be updated");
 								static_assert(TableCheckRequired::value or Policies::template _no_unknown_tables<Assignment>::value, "assignment uses tables unknown to this statement in add_set()");
 
-								using ok = ::sqlpp::detail::all_t<sqlpp::detail::identity_t, 
-											_is_dynamic, 
-											is_assignment_t<Assignment>, 
-											sqlpp::detail::not_t<must_not_update_t, typename Assignment::_column_t>>;
+								using ok = ::sqlpp::detail::all_t<
+											_is_dynamic::value, 
+											is_assignment_t<Assignment>::value, 
+											not must_not_update_t<typename Assignment::_column_t>::value>;
 
 								_add_set_impl(assignment, ok()); // dispatch to prevent compile messages after the static_assert
 							}
diff --git a/include/sqlpp11/vendor/using.h b/include/sqlpp11/vendor/using.h
index eaaea22f..64415e9d 100644
--- a/include/sqlpp11/vendor/using.h
+++ b/include/sqlpp11/vendor/using.h
@@ -49,7 +49,7 @@ namespace sqlpp
 
 				static_assert(not ::sqlpp::detail::has_duplicates<Tables...>::value, "at least one duplicate argument detected in using()");
 
-				static_assert(::sqlpp::detail::all_t<is_table_t, Tables...>::value, "at least one argument is not an table in using()");
+				static_assert(::sqlpp::detail::all_t<is_table_t<Tables>::value...>::value, "at least one argument is not an table in using()");
 
 				using _table_set = ::sqlpp::detail::make_joined_set_t<typename Tables::_table_set...>;
 
@@ -72,7 +72,7 @@ namespace sqlpp
 								static_assert(_is_dynamic::value, "add_using must not be called for static using()");
 								static_assert(is_table_t<Table>::value, "invalid table argument in add_using()");
 
-								using ok = ::sqlpp::detail::all_t<sqlpp::detail::identity_t, _is_dynamic, is_table_t<Table>>;
+								using ok = ::sqlpp::detail::all_t<_is_dynamic::value, is_table_t<Table>::value>;
 
 								_add_using_impl(table, ok()); // dispatch to prevent compile messages after the static_assert
 							}
diff --git a/include/sqlpp11/vendor/where.h b/include/sqlpp11/vendor/where.h
index dad97616..63882e0a 100644
--- a/include/sqlpp11/vendor/where.h
+++ b/include/sqlpp11/vendor/where.h
@@ -48,7 +48,7 @@ namespace sqlpp
 
 				static_assert(_is_dynamic::value or sizeof...(Expressions), "at least one expression argument required in where()");
 				static_assert(sqlpp::detail::none_t<is_assignment_t<Expressions>::value...>::value, "at least one argument is an assignment in where()");
-				static_assert(sqlpp::detail::all_t<is_expression_t, Expressions...>::value, "at least one argument is not valid expression in where()");
+				static_assert(sqlpp::detail::all_t<is_expression_t<Expressions>::value...>::value, "at least one argument is not valid expression in where()");
 
 				using _parameter_list_t = typename make_parameter_list_t<_parameter_tuple_t>::type;
 
@@ -80,7 +80,7 @@ namespace sqlpp
 								static_assert(is_expression_t<Expression>::value, "invalid expression argument in add_where()");
 								static_assert(TableCheckRequired::value or Policies::template _no_unknown_tables<Expression>::value, "expression uses tables unknown to this statement in add_where()");
 
-								using ok = ::sqlpp::detail::all_t<sqlpp::detail::identity_t, _is_dynamic, is_expression_t<Expression>>;
+								using ok = ::sqlpp::detail::all_t<_is_dynamic::value, is_expression_t<Expression>::value>;
 
 								_add_where_impl(expression, ok()); // dispatch to prevent compile messages after the static_assert
 							}