diff --git a/include/evalhyd/detail/determinist/evaluator.hpp b/include/evalhyd/detail/determinist/evaluator.hpp
index 165a2c39a8c3e967cbd88e419765abd0d91144dd..0aeca94ea846977a1e1525a6c69a980ca038198f 100644
--- a/include/evalhyd/detail/determinist/evaluator.hpp
+++ b/include/evalhyd/detail/determinist/evaluator.hpp
@@ -27,7 +27,7 @@ namespace evalhyd
             const XD2& q_obs;
             const XD2& q_prd;
             // members for optional input data
-            XB3 t_msk;
+            xt::xtensor<bool, 3> t_msk;
             const std::vector<xt::xkeep_slice<int>>& b_exp;
 
             // members for dimensions
diff --git a/include/evalhyd/detail/probabilist/evaluator.hpp b/include/evalhyd/detail/probabilist/evaluator.hpp
index 93111a14bce6dc8e9352dc555b5eb821047c0e1b..128ca2802a4b019417193543608511eccfd67fc1 100644
--- a/include/evalhyd/detail/probabilist/evaluator.hpp
+++ b/include/evalhyd/detail/probabilist/evaluator.hpp
@@ -34,7 +34,7 @@ namespace evalhyd
             const XD2& _q_thr;
             const xt::xtensor<double, 1>& _c_lvl;
             xtl::xoptional<const std::string, bool> _events;
-            XB4 t_msk;
+            xt::xtensor<bool, 4> t_msk;
             const std::vector<xt::xkeep_slice<int>>& b_exp;
 
             // member for "reproducible randomness"