diff --git a/include/pagmo/algorithms/cstrs_self_adaptive.hpp b/include/pagmo/algorithms/cstrs_self_adaptive.hpp
index 576d9a684..2b1132ea9 100644
--- a/include/pagmo/algorithms/cstrs_self_adaptive.hpp
+++ b/include/pagmo/algorithms/cstrs_self_adaptive.hpp
@@ -96,6 +96,9 @@ struct PAGMO_DLL_PUBLIC penalized_udp {
     // The bounds are unchanged
     std::pair<vector_double, vector_double> get_bounds() const;
 
+    // The integer dimension is unchanged
+    vector_double::size_type get_nix() const;
+
     // The fitness computation
     vector_double fitness(const vector_double &) const;
 
diff --git a/src/algorithms/cstrs_self_adaptive.cpp b/src/algorithms/cstrs_self_adaptive.cpp
index d065d5571..cffebb75c 100644
--- a/src/algorithms/cstrs_self_adaptive.cpp
+++ b/src/algorithms/cstrs_self_adaptive.cpp
@@ -80,6 +80,12 @@ std::pair<vector_double, vector_double> penalized_udp::get_bounds() const
     return m_pop_ptr->get_problem().get_bounds();
 }
 
+// The integer dimension is unchanged
+vector_double::size_type penalized_udp::get_nix() const
+{
+    return m_pop_ptr->get_problem().get_nix();
+}
+
 // The fitness computation
 vector_double penalized_udp::fitness(const vector_double &x) const
 {
diff --git a/tests/cstrs_self_adaptive.cpp b/tests/cstrs_self_adaptive.cpp
index 007f62e62..30a082198 100644
--- a/tests/cstrs_self_adaptive.cpp
+++ b/tests/cstrs_self_adaptive.cpp
@@ -65,6 +65,7 @@ BOOST_AUTO_TEST_CASE(penalized_problem_construction)
     BOOST_CHECK_EQUAL(udp_p.m_f_hat_down.size(), udp.get_nf());
     BOOST_CHECK_EQUAL(udp_p.m_f_hat_up.size(), udp.get_nf());
     BOOST_CHECK_EQUAL(udp_p.m_f_hat_round.size(), udp.get_nf());
+    BOOST_CHECK_EQUAL(udp_p.get_nix(), udp.get_nix());
     BOOST_CHECK_EQUAL(udp_p.m_fitness_map.size(), NP);
     // We also test get bounds here
     BOOST_CHECK(udp_p.get_bounds() == udp.get_bounds());