diff --git a/include/sqlpp11/in.h b/include/sqlpp11/in.h
index 5653a3dc..9a864363 100644
--- a/include/sqlpp11/in.h
+++ b/include/sqlpp11/in.h
@@ -76,8 +76,8 @@ namespace sqlpp
 			template<typename Db>
 				void serialize(std::ostream& os, Db& db) const
 				{
-					static_assert(NotInverted and Db::_supports_in
-							or _inverted and Db::_supports_not_in, "in() and/or not_in() not supported by current database");
+					static_assert((NotInverted and Db::_supports_in)
+							or (_inverted and Db::_supports_not_in), "in() and/or not_in() not supported by current database");
 					_operand.serialize(os, db);
 					os << (_inverted ? " NOT IN(" : " IN(");
 					detail::serialize_tuple(os, db, _args, ',');
diff --git a/include/sqlpp11/is_null.h b/include/sqlpp11/is_null.h
index a9dc2d93..6da8b1ba 100644
--- a/include/sqlpp11/is_null.h
+++ b/include/sqlpp11/is_null.h
@@ -73,8 +73,8 @@ namespace sqlpp
 			template<typename Db>
 				void serialize(std::ostream& os, Db& db) const
 				{
-					static_assert(NotInverted and Db::_supports_is_null
-							or _inverted and Db::_supports_is_not_null, "is_null() and/or is_not_null() not supported by current database");
+					static_assert((NotInverted and Db::_supports_is_null)
+							or (_inverted and Db::_supports_is_not_null), "is_null() and/or is_not_null() not supported by current database");
 					_operand.serialize(os, db);
 					os << (_inverted ? " IS NOT NULL" : " IS NULL");
 				}