diff --git a/src/vt/topos/mapping/dense/dense.h b/src/vt/topos/mapping/dense/dense.h
index ed819498e2..83598acfab 100644
--- a/src/vt/topos/mapping/dense/dense.h
+++ b/src/vt/topos/mapping/dense/dense.h
@@ -74,6 +74,7 @@ using IdxPtr = Index*;
 template <typename T = IdxBase> using Idx1DPtr = IdxType1D<T>*;
 template <typename T = IdxBase> using Idx2DPtr = IdxType2D<T>*;
 template <typename T = IdxBase> using Idx3DPtr = IdxType3D<T>*;
+template <typename T, typename N> using IdxNDPtr = vt::index::IdxType<T, N>*;
 
 template <typename Idx, index::NumDimensionsType ndim>
 NodeType denseBlockMap(IdxPtr<Idx> idx, IdxPtr<Idx> max_idx, NodeType nnodes);
@@ -84,6 +85,8 @@ template <typename T = IdxBase>
 NodeType defaultDenseIndex2DMap(Idx2DPtr<T> idx, Idx2DPtr<T> max, NodeType n);
 template <typename T = IdxBase>
 NodeType defaultDenseIndex3DMap(Idx3DPtr<T> idx, Idx3DPtr<T> max, NodeType n);
+template <typename T, typename N>
+NodeType defaultDenseIndex3DMap(IdxNDPtr<T,N> idx, IdxNDPtr<T,N> max, NodeType n);
 
 template <typename T = IdxBase>
 NodeType dense1DRoundRobinMap(  Idx1DPtr<T> idx, Idx1DPtr<T> max, NodeType n);
diff --git a/tests/unit/collection/test_construct.cc b/tests/unit/collection/test_construct.cc
index db6065eabe..21250b5170 100644
--- a/tests/unit/collection/test_construct.cc
+++ b/tests/unit/collection/test_construct.cc
@@ -64,6 +64,23 @@ struct ColMsg : CollectionMessage<TestCol> { };
 using CollectionTestTypes = testing::Types<default_::TestCol>;
 using CollectionTestDistTypes = testing::Types<default_::TestCol>;
 
+using TestRange = vt::index::IdxType<vt::IdxBase, 4>;
+struct TestColMulti : Collection<TestColMulti, TestRange>{
+
+};
+
+struct TestCollectionConst : TestParallelHarness {};
+
+TEST_F(TestCollectionConst, test_collection_create) {
+    auto rng = TestRange(6, 6, 6, 6);
+    theCollection()->constructCollective<TestColMulti>(
+      rng,[=](TestRange my_idx) {
+        return std::make_unique<TestColMulti>();
+      }
+    );
+    // auto proxy = ConstructParams<TestColMulti>::constructCollective(rng);
+}
+
 INSTANTIATE_TYPED_TEST_SUITE_P(
   test_construct_simple, TestConstruct, CollectionTestTypes, DEFAULT_NAME_GEN
 );
diff --git a/tests/unit/collection/test_construct_no_idx.extended.cc b/tests/unit/collection/test_construct_no_idx.extended.cc
index bc96984b3e..321b2f9256 100644
--- a/tests/unit/collection/test_construct_no_idx.extended.cc
+++ b/tests/unit/collection/test_construct_no_idx.extended.cc
@@ -57,6 +57,7 @@ struct ColMsg;
 struct TestCol : Collection<TestCol,vt::Index1D> {
   using MsgType = ColMsg;
 };
+
 struct ColMsg : CollectionMessage<TestCol> {};
 } /* end namespace multi_param_no_idx_ */