diff --git a/dev/make-root/rntuple_atomic_bitset.C b/dev/make-root/rntuple_atomic_bitset.C
new file mode 100644
index 0000000..45b8f37
--- /dev/null
+++ b/dev/make-root/rntuple_atomic_bitset.C
@@ -0,0 +1,34 @@
+/* https://root.cern/doc/master/ntpl001__staff_8C.html */
+R__LOAD_LIBRARY(ROOTNTuple)
+#include <ROOT/RField.hxx>
+#include <ROOT/RNTuple.hxx>
+#include <ROOT/RNTupleModel.hxx>
+#include <ROOT/RNTupleWriter.hxx>
+#include <ROOT/RRawFile.hxx>
+
+#include <atomic>
+#include <bitset>
+
+using RNTupleModel = ROOT::Experimental::RNTupleModel;
+using RNTupleWriter = ROOT::Experimental::RNTupleWriter;
+
+void rntuple_atomic_bitset() {
+  std::string rootFileName{"test_ntuple_atomic_bitset.root"};
+  auto model = RNTupleModel::Create();
+  auto atomic_int_field = model->MakeField<std::atomic<int>>("atomic_int");
+  auto bitset_field = model->MakeField<std::bitset<42>>("bitset");
+  auto ntuple =
+      RNTupleWriter::Recreate(std::move(model), "ntuple", rootFileName);
+
+  *atomic_int_field = 1;
+  *bitset_field = std::bitset<42>(42);
+  ntuple->Fill();
+
+  *atomic_int_field = 2;
+  *bitset_field |= 0b1010101010101010;
+  ntuple->Fill();
+
+  *atomic_int_field = 3;
+  *bitset_field &= 0b1100110011001100;
+  ntuple->Fill();
+}
diff --git a/dev/make-root/rntuple_emptystruct_invalidvar.C b/dev/make-root/rntuple_emptystruct_invalidvar.C
new file mode 100644
index 0000000..79d1b6b
--- /dev/null
+++ b/dev/make-root/rntuple_emptystruct_invalidvar.C
@@ -0,0 +1,46 @@
+/* https://root.cern/doc/master/ntpl001__staff_8C.html */
+R__LOAD_LIBRARY(ROOTNTuple)
+#include <ROOT/RField.hxx>
+#include <ROOT/RNTuple.hxx>
+#include <ROOT/RNTupleModel.hxx>
+#include <ROOT/RNTupleWriter.hxx>
+#include <ROOT/RRawFile.hxx>
+
+#include <cassert>
+#include <variant>
+
+using RNTupleModel = ROOT::Experimental::RNTupleModel;
+using RNTupleWriter = ROOT::Experimental::RNTupleWriter;
+
+struct EmptyStruct {};
+
+struct StructForVariant {
+   int i;
+   StructForVariant() = default;
+   StructForVariant(const StructForVariant &) { throw std::runtime_error("copy ctor"); }
+   StructForVariant &operator=(const StructForVariant &) = default;
+};
+
+void rntuple_emptystruct_invalidvar() {
+  std::string rootFileName{"test_ntuple_emptystruct_invalidvar.root"};
+  auto model = RNTupleModel::Create();
+  auto empty_struct_field = model->MakeField<EmptyStruct>("empty_struct");
+  auto variant_field = model->MakeField<std::variant<int,StructForVariant>>("variant");
+  auto ntuple =
+      RNTupleWriter::Recreate(std::move(model), "ntuple", rootFileName);
+
+  *empty_struct_field = EmptyStruct{};
+  *variant_field = 1; // valid state
+  ntuple->Fill();
+
+  *variant_field = { 1 }; // valid state
+  ntuple->Fill();
+
+  try {
+    *variant_field = StructForVariant(); // invalid state
+  } catch (const std::runtime_error &e) {
+    std::cerr << "Caught exception: " << e.what() << std::endl;
+  }
+  assert(variant_field->valueless_by_exception());
+  ntuple->Fill();
+}
diff --git a/src/skhep_testdata/data/test_ntuple_atomic_bitset.root b/src/skhep_testdata/data/test_ntuple_atomic_bitset.root
new file mode 100644
index 0000000..6ca24dc
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diff --git a/src/skhep_testdata/data/test_ntuple_emptystruct_invalidvar.root b/src/skhep_testdata/data/test_ntuple_emptystruct_invalidvar.root
new file mode 100644
index 0000000..4d06ed1
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