diff --git a/common/unified/multigrid/uniform_coarsening_kernels.cpp b/common/unified/multigrid/uniform_coarsening_kernels.cpp
index 3dcaf1279e4..27628cd6fd3 100644
--- a/common/unified/multigrid/uniform_coarsening_kernels.cpp
+++ b/common/unified/multigrid/uniform_coarsening_kernels.cpp
@@ -78,13 +78,15 @@ void fill_incremental_indices(std::shared_ptr<const DefaultExecutor> exec,
                               size_type num_jumps,
                               Array<IndexType>* coarse_rows)
 {
-    IndexType num_elems = (coarse_rows->get_num_elems() + 1) / num_jumps;
+    IndexType num_elems = (coarse_rows->get_num_elems());
     run_kernel(
         exec,
-        [] GKO_KERNEL(auto tidx, auto num_jumps, auto coarse_data) {
-            coarse_data[tidx] = tidx / num_jumps;
+        [] GKO_KERNEL(auto tidx, auto num_jumps, auto coarse_data, auto size) {
+            if (tidx % num_jumps == 0 && tidx < size) {
+                coarse_data[tidx] = tidx / num_jumps;
+            }
         },
-        num_elems * num_jumps, num_jumps, coarse_rows->get_data());
+        num_elems, num_jumps, coarse_rows->get_data(), num_elems);
 }
 
 GKO_INSTANTIATE_FOR_EACH_INDEX_TYPE(
diff --git a/reference/test/multigrid/uniform_coarsening_kernels.cpp b/reference/test/multigrid/uniform_coarsening_kernels.cpp
index c1c50f7b23f..c1bcc76c978 100644
--- a/reference/test/multigrid/uniform_coarsening_kernels.cpp
+++ b/reference/test/multigrid/uniform_coarsening_kernels.cpp
@@ -293,6 +293,27 @@ TYPED_TEST(UniformCoarsening, Generate)
 }
 
 
+TYPED_TEST(UniformCoarsening, FillIncrementalIndicesWorks)
+{
+    using index_type = typename TestFixture::index_type;
+    auto c2_rows =
+        gko::Array<index_type>(this->exec, {0, -1, 1, -1, 2, -1, 3, -1, 4, -1});
+    auto c3_rows = gko::Array<index_type>(this->exec,
+                                          {0, -1, -1, 1, -1, -1, 2, -1, -1, 3});
+    auto c_rows = gko::Array<index_type>(this->exec, 10);
+    c_rows.fill(-gko::one<index_type>());
+
+    gko::kernels::reference::uniform_coarsening::fill_incremental_indices(
+        this->exec, 2, &c_rows);
+    GKO_ASSERT_ARRAY_EQ(c_rows, c2_rows);
+
+    c_rows.fill(-gko::one<index_type>());
+    gko::kernels::reference::uniform_coarsening::fill_incremental_indices(
+        this->exec, 3, &c_rows);
+    GKO_ASSERT_ARRAY_EQ(c_rows, c3_rows);
+}
+
+
 TYPED_TEST(UniformCoarsening, CoarseFineRestrictApply)
 {
     auto uniform_coarsening =
diff --git a/test/multigrid/uniform_coarsening_kernels.cpp b/test/multigrid/uniform_coarsening_kernels.cpp
index 5e57740a83d..c84ce0c63b6 100644
--- a/test/multigrid/uniform_coarsening_kernels.cpp
+++ b/test/multigrid/uniform_coarsening_kernels.cpp
@@ -81,6 +81,7 @@ class UniformCoarsening : public ::testing::Test {
     {
         ref = gko::ReferenceExecutor::create();
         init_executor(ref, exec);
+        m = 597;
     }
 
     void TearDown()
@@ -113,7 +114,6 @@ class UniformCoarsening : public ::testing::Test {
 
     void initialize_data(gko::size_type num_jumps = 2)
     {
-        m = 597;
         coarse_rows = gen_coarse_array(m, num_jumps);
         c_dim = (coarse_rows.get_num_elems() + 1) / num_jumps;
 
@@ -153,8 +153,8 @@ class UniformCoarsening : public ::testing::Test {
 TEST_F(UniformCoarsening, FillIncrementalIndicesIsEquivalentToRef)
 {
     auto c_rows = gko::Array<index_type>(ref, m);
-    auto d_c_rows = gko::Array<index_type>(exec, m);
-    d_c_rows = c_rows;
+    c_rows.fill(-gko::one<index_type>());
+    auto d_c_rows = gko::Array<index_type>(exec, c_rows);
 
     {
         gko::size_type num_jumps = 2;
@@ -166,6 +166,8 @@ TEST_F(UniformCoarsening, FillIncrementalIndicesIsEquivalentToRef)
     }
     {
         gko::size_type num_jumps = 3;
+        c_rows.fill(-gko::one<index_type>());
+        d_c_rows.fill(-gko::one<index_type>());
         gko::kernels::reference::uniform_coarsening::fill_incremental_indices(
             ref, num_jumps, &c_rows);
         gko::kernels::EXEC_NAMESPACE::uniform_coarsening::
@@ -174,6 +176,8 @@ TEST_F(UniformCoarsening, FillIncrementalIndicesIsEquivalentToRef)
     }
     {
         gko::size_type num_jumps = 47;
+        c_rows.fill(-gko::one<index_type>());
+        d_c_rows.fill(-gko::one<index_type>());
         gko::kernels::reference::uniform_coarsening::fill_incremental_indices(
             ref, num_jumps, &c_rows);
         gko::kernels::EXEC_NAMESPACE::uniform_coarsening::
@@ -203,60 +207,60 @@ TEST_F(UniformCoarsening, FillRestrictOpIsEquivalentToRef)
     GKO_ASSERT_MTX_NEAR(restrict_op, d_restrict_op, r<value_type>::value);
 }
 
-// TODO: Fix for OpenMP
-// TEST_F(UniformCoarsening, GenerateMgLevelIsEquivalentToRef)
-// {
-//     gko::size_type num_jumps = 2;
-//     initialize_data(num_jumps);
-//     auto mg_level_factory =
-//         gko::multigrid::UniformCoarsening<value_type, int>::build()
-//             .with_num_jumps(num_jumps)
-//             .with_skip_sorting(true)
-//             .on(ref);
-//     auto d_mg_level_factory =
-//         gko::multigrid::UniformCoarsening<value_type, int>::build()
-//             .with_num_jumps(num_jumps)
-//             .with_skip_sorting(true)
-//             .on(exec);
-
-//     auto mg_level = mg_level_factory->generate(system_mtx);
-//     auto d_mg_level = d_mg_level_factory->generate(d_system_mtx);
-
-//     GKO_ASSERT_MTX_NEAR(gko::as<Csr>(d_mg_level->get_prolong_op()),
-//                         gko::as<Csr>(mg_level->get_prolong_op()),
-//                         r<value_type>::value);
-//     GKO_ASSERT_MTX_NEAR(gko::as<Csr>(d_mg_level->get_restrict_op()),
-//                         gko::as<Csr>(mg_level->get_restrict_op()),
-//                         r<value_type>::value);
-//     GKO_ASSERT_MTX_NEAR(gko::as<Csr>(d_mg_level->get_coarse_op()),
-//                         gko::as<Csr>(mg_level->get_coarse_op()),
-//                         r<value_type>::value);
-// }
-
-
-// TEST_F(UniformCoarsening, GenerateMgLevelIsEquivalentToRefOnUnsortedMatrix)
-// {
-//     initialize_data();
-//     gko::test::unsort_matrix(gko::lend(system_mtx), rand_engine);
-//     d_system_mtx = gko::clone(exec, system_mtx);
-//     auto mg_level_factory =
-//         gko::multigrid::UniformCoarsening<value_type, int>::build().on(ref);
-//     auto d_mg_level_factory =
-//         gko::multigrid::UniformCoarsening<value_type, int>::build().on(exec);
-
-//     auto mg_level = mg_level_factory->generate(system_mtx);
-//     auto d_mg_level = d_mg_level_factory->generate(d_system_mtx);
-
-//     GKO_ASSERT_MTX_NEAR(gko::as<Csr>(d_mg_level->get_prolong_op()),
-//                         gko::as<Csr>(mg_level->get_prolong_op()),
-//                         r<value_type>::value);
-//     GKO_ASSERT_MTX_NEAR(gko::as<Csr>(d_mg_level->get_restrict_op()),
-//                         gko::as<Csr>(mg_level->get_restrict_op()),
-//                         r<value_type>::value);
-//     GKO_ASSERT_MTX_NEAR(gko::as<Csr>(d_mg_level->get_coarse_op()),
-//                         gko::as<Csr>(mg_level->get_coarse_op()),
-//                         r<value_type>::value);
-// }
+
+TEST_F(UniformCoarsening, GenerateMgLevelIsEquivalentToRef)
+{
+    gko::size_type num_jumps = 2;
+    initialize_data(num_jumps);
+    auto mg_level_factory =
+        gko::multigrid::UniformCoarsening<value_type, int>::build()
+            .with_num_jumps(static_cast<unsigned>(num_jumps))
+            .with_skip_sorting(true)
+            .on(ref);
+    auto d_mg_level_factory =
+        gko::multigrid::UniformCoarsening<value_type, int>::build()
+            .with_num_jumps(static_cast<unsigned>(num_jumps))
+            .with_skip_sorting(true)
+            .on(exec);
+
+    auto mg_level = mg_level_factory->generate(system_mtx);
+    auto d_mg_level = d_mg_level_factory->generate(d_system_mtx);
+
+    GKO_ASSERT_MTX_NEAR(gko::as<Csr>(d_mg_level->get_prolong_op()),
+                        gko::as<Csr>(mg_level->get_prolong_op()),
+                        r<value_type>::value);
+    GKO_ASSERT_MTX_NEAR(gko::as<Csr>(d_mg_level->get_restrict_op()),
+                        gko::as<Csr>(mg_level->get_restrict_op()),
+                        r<value_type>::value);
+    GKO_ASSERT_MTX_NEAR(gko::as<Csr>(d_mg_level->get_coarse_op()),
+                        gko::as<Csr>(mg_level->get_coarse_op()),
+                        r<value_type>::value);
+}
+
+
+TEST_F(UniformCoarsening, GenerateMgLevelIsEquivalentToRefOnUnsortedMatrix)
+{
+    initialize_data();
+    gko::test::unsort_matrix(gko::lend(system_mtx), rand_engine);
+    d_system_mtx = gko::clone(exec, system_mtx);
+    auto mg_level_factory =
+        gko::multigrid::UniformCoarsening<value_type, int>::build().on(ref);
+    auto d_mg_level_factory =
+        gko::multigrid::UniformCoarsening<value_type, int>::build().on(exec);
+
+    auto mg_level = mg_level_factory->generate(system_mtx);
+    auto d_mg_level = d_mg_level_factory->generate(d_system_mtx);
+
+    GKO_ASSERT_MTX_NEAR(gko::as<Csr>(d_mg_level->get_prolong_op()),
+                        gko::as<Csr>(mg_level->get_prolong_op()),
+                        r<value_type>::value);
+    GKO_ASSERT_MTX_NEAR(gko::as<Csr>(d_mg_level->get_restrict_op()),
+                        gko::as<Csr>(mg_level->get_restrict_op()),
+                        r<value_type>::value);
+    GKO_ASSERT_MTX_NEAR(gko::as<Csr>(d_mg_level->get_coarse_op()),
+                        gko::as<Csr>(mg_level->get_coarse_op()),
+                        r<value_type>::value);
+}
 
 
 }  // namespace