diff --git a/c2h/generators.cu b/c2h/generators.cu
index 8044eabe6fe..4abdfe896ea 100644
--- a/c2h/generators.cu
+++ b/c2h/generators.cu
@@ -478,15 +478,15 @@ template void
 init_key_segments(const c2h::device_vector<std::uint32_t>& segment_offsets, float* out, std::size_t element_size);
 template void init_key_segments(
   const c2h::device_vector<std::uint32_t>& segment_offsets, custom_type_state_t* out, std::size_t element_size);
-#ifdef _CCCL_HAS_NVFP16
+#ifdef TEST_HALF_T
 template void
 init_key_segments(const c2h::device_vector<std::uint32_t>& segment_offsets, half_t* out, std::size_t element_size);
-#endif // _CCCL_HAS_NVFP16
+#endif // TEST_HALF_T
 
-#ifdef _CCCL_HAS_NVBF16
+#ifdef TEST_BF_T
 template void
 init_key_segments(const c2h::device_vector<std::uint32_t>& segment_offsets, bfloat16_t* out, std::size_t element_size);
-#endif // _CCCL_HAS_NVBF16
+#endif // TEST_BF_T
 } // namespace detail
 
 template <typename T>
@@ -552,15 +552,15 @@ INSTANTIATE(double);
 INSTANTIATE(bool);
 INSTANTIATE(char);
 
-#ifdef _CCCL_HAS_NVFP16
+#ifdef TEST_HALF_T
 INSTANTIATE(half_t);
 INSTANTIATE(__half);
-#endif // _CCCL_HAS_NVFP16
+#endif // TEST_HALF_T
 
-#ifdef _CCCL_HAS_NVBF16
+#ifdef TEST_BF_T
 INSTANTIATE(bfloat16_t);
 INSTANTIATE(__nv_bfloat16);
-#endif // _CCCL_HAS_NVBF16
+#endif // TEST_BF_T
 
 #undef INSTANTIATE_RND
 #undef INSTANTIATE_MOD
diff --git a/c2h/include/c2h/extended_types.h b/c2h/include/c2h/extended_types.h
index d8e53acd71e..753e225f15a 100644
--- a/c2h/include/c2h/extended_types.h
+++ b/c2h/include/c2h/extended_types.h
@@ -30,11 +30,15 @@
 #include <cuda/__cccl_config>
 
 #ifndef TEST_HALF_T
-#  define TEST_HALF_T _CCCL_HAS_NVFP16
+#  if defined(_CCCL_HAS_NVFP16) && defined(_LIBCUDACXX_HAS_NVFP16)
+#    define TEST_HALF_T
+#  endif
 #endif
 
 #ifndef TEST_BF_T
-#  define TEST_BF_T _CCCL_HAS_NVBF16
+#  if defined(_CCCL_HAS_NVBF16) && defined(_LIBCUDACXX_HAS_NVBF16)
+#    define TEST_BF_T
+#  endif
 #endif
 
 #ifdef TEST_HALF_T
diff --git a/cub/test/catch2_segmented_sort_helper.cuh b/cub/test/catch2_segmented_sort_helper.cuh
index f8a081a125a..5f8b2b09c62 100644
--- a/cub/test/catch2_segmented_sort_helper.cuh
+++ b/cub/test/catch2_segmented_sort_helper.cuh
@@ -265,7 +265,7 @@ struct unwrap_value_t_impl
   using type = T;
 };
 
-#if TEST_HALF_T
+#ifdef TEST_HALF_T
 template <>
 struct unwrap_value_t_impl<half_t>
 {
@@ -273,7 +273,7 @@ struct unwrap_value_t_impl<half_t>
 };
 #endif
 
-#if TEST_BF_T
+#ifdef TEST_BF_T
 template <>
 struct unwrap_value_t_impl<bfloat16_t>
 {
diff --git a/cub/test/catch2_test_device_histogram.cu b/cub/test/catch2_test_device_histogram.cu
index e258fb4bcb6..2ed5d621661 100644
--- a/cub/test/catch2_test_device_histogram.cu
+++ b/cub/test/catch2_test_device_histogram.cu
@@ -69,7 +69,7 @@ auto cast_if_half_pointer(T* p) -> T*
   return p;
 }
 
-#if TEST_HALF_T
+#ifdef TEST_HALF_T
 auto cast_if_half_pointer(half_t* p) -> __half*
 {
   return reinterpret_cast<__half*>(p);
@@ -412,7 +412,7 @@ using types =
                  std::uint32_t,
                  std::int64_t,
                  std::uint64_t,
-#if TEST_HALF_T
+#ifdef TEST_HALF_T
                  half_t,
 #endif
                  float,
diff --git a/cub/test/catch2_test_device_reduce.cu b/cub/test/catch2_test_device_reduce.cu
index d6cfdb11521..fb046a3c7d5 100644
--- a/cub/test/catch2_test_device_reduce.cu
+++ b/cub/test/catch2_test_device_reduce.cu
@@ -77,14 +77,13 @@ using full_type_list = c2h::type_list<type_pair<uchar3>, type_pair<ulonglong4>>;
 // clang-format off
 using full_type_list = c2h::type_list<
 type_pair<custom_t>
-#if TEST_HALF_T
-, type_pair<half_t> // testing half
-#endif
-#if TEST_BF_T
-, type_pair<bfloat16_t> // testing bf16
-
+#ifdef TEST_HALF_T
+, type_pair<half_t>
+#endif // TEST_HALF_T
+#ifdef TEST_BF_T
+, type_pair<bfloat16_t>
+#endif // TEST_BF_T
 >;
-#endif
 // clang-format on
 #elif TEST_TYPES == 4
 // DPX SIMD instructions
diff --git a/cub/test/catch2_test_device_reduce.cuh b/cub/test/catch2_test_device_reduce.cuh
index ed9a806d19e..6fbdfa9b4c5 100644
--- a/cub/test/catch2_test_device_reduce.cuh
+++ b/cub/test/catch2_test_device_reduce.cuh
@@ -46,7 +46,7 @@
 #include <c2h/test_util_vec.h>
 #include <nv/target>
 
-#if TEST_HALF_T
+#ifdef TEST_HALF_T
 // Half support is provided by SM53+. We currently test against a few older architectures.
 // The specializations below can be removed once we drop these architectures.
 
@@ -107,8 +107,13 @@ __host__ __device__ __forceinline__ //
 
   return a;
 }
+
+CUB_NAMESPACE_END
+
 #endif // TEST_HALF_T
 
+CUB_NAMESPACE_BEGIN
+
 /**
  * @brief Introduces the required NumericTraits for `c2h::custom_type_t`.
  */
@@ -173,7 +178,7 @@ struct ExtendedFloatSum
     return result;
   }
 
-#if TEST_HALF_T
+#ifdef TEST_HALF_T
   __host__ __device__ __half operator()(__half a, __half b) const
   {
     uint16_t result = this->operator()(half_t{a}, half_t(b)).raw();
@@ -181,7 +186,7 @@ struct ExtendedFloatSum
   }
 #endif
 
-#if TEST_BF_T
+#ifdef TEST_BF_T
   __device__ __nv_bfloat16 operator()(__nv_bfloat16 a, __nv_bfloat16 b) const
   {
     uint16_t result = this->operator()(bfloat16_t{a}, bfloat16_t(b)).raw();
@@ -196,7 +201,7 @@ inline It unwrap_it(It it)
   return it;
 }
 
-#if TEST_HALF_T
+#ifdef TEST_HALF_T
 inline __half* unwrap_it(half_t* it)
 {
   return reinterpret_cast<__half*>(it);
@@ -211,7 +216,7 @@ inline thrust::constant_iterator<__half, OffsetT> unwrap_it(thrust::constant_ite
 }
 #endif
 
-#if TEST_BF_T
+#ifdef TEST_BF_T
 inline __nv_bfloat16* unwrap_it(bfloat16_t* it)
 {
   return reinterpret_cast<__nv_bfloat16*>(it);
diff --git a/cub/test/catch2_test_device_reduce_by_key.cu b/cub/test/catch2_test_device_reduce_by_key.cu
index ee8726219f2..6d21e9c64f1 100644
--- a/cub/test/catch2_test_device_reduce_by_key.cu
+++ b/cub/test/catch2_test_device_reduce_by_key.cu
@@ -58,10 +58,10 @@ using full_type_list = c2h::type_list<type_triple<uchar3, uchar3, custom_t>, typ
 // clang-format off
 using full_type_list = c2h::type_list<
 type_triple<custom_t>
-#if TEST_HALF_T
+#ifdef TEST_HALF_T
 , type_triple<half_t> // testing half
 #endif
-#if TEST_BF_T
+#ifdef TEST_BF_T
 , type_triple<bfloat16_t> // testing bf16
 #endif
 >;
diff --git a/cub/test/catch2_test_device_scan.cu b/cub/test/catch2_test_device_scan.cu
index d9cf517f55d..4b2e5820d27 100644
--- a/cub/test/catch2_test_device_scan.cu
+++ b/cub/test/catch2_test_device_scan.cu
@@ -64,10 +64,10 @@ using full_type_list = c2h::type_list<type_pair<uchar3>, type_pair<ulonglong4>>;
 // clang-format off
 using full_type_list = c2h::type_list<
 type_pair<custom_t>
-#if TEST_HALF_T
+#ifdef TEST_HALF_T
 , type_pair<half_t> // testing half
 #endif
-#if TEST_BF_T
+#ifdef TEST_BF_T
 , type_pair<bfloat16_t> // testing bf16
 #endif
 >;
diff --git a/cub/test/catch2_test_device_scan_by_key.cu b/cub/test/catch2_test_device_scan_by_key.cu
index 6942d22d09e..6b6b0e9ef7a 100644
--- a/cub/test/catch2_test_device_scan_by_key.cu
+++ b/cub/test/catch2_test_device_scan_by_key.cu
@@ -69,10 +69,10 @@ using full_type_list =
 // clang-format off
 using full_type_list = c2h::type_list<
 type_quad<custom_t, custom_t, custom_t>
-#if TEST_HALF_T
+#ifdef TEST_HALF_T
 , type_quad<half_t> // testing half
 #endif
-#if TEST_BF_T
+#ifdef TEST_BF_T
 , type_quad<bfloat16_t> // testing bf16
 #endif
 >;
diff --git a/cub/test/catch2_test_device_segmented_reduce.cu b/cub/test/catch2_test_device_segmented_reduce.cu
index c524a7ef753..5fd75b15248 100644
--- a/cub/test/catch2_test_device_segmented_reduce.cu
+++ b/cub/test/catch2_test_device_segmented_reduce.cu
@@ -65,10 +65,10 @@ using full_type_list = c2h::type_list<type_pair<uchar3>, type_pair<ulonglong4>>;
 // clang-format off
 using full_type_list = c2h::type_list<
 type_pair<custom_t>
-#if TEST_HALF_T
+#ifdef TEST_HALF_T
 , type_pair<half_t> // testing half
 #endif
-#if TEST_BF_T
+#ifdef TEST_BF_T
 , type_pair<bfloat16_t> // testing bf16
 #endif
 >;
diff --git a/cub/test/catch2_test_device_segmented_sort_keys.cu b/cub/test/catch2_test_device_segmented_sort_keys.cu
index 3d392e8e8f6..a4d27d7df30 100644
--- a/cub/test/catch2_test_device_segmented_sort_keys.cu
+++ b/cub/test/catch2_test_device_segmented_sort_keys.cu
@@ -28,6 +28,7 @@
 #include "insert_nested_NVTX_range_guard.h"
 // above header needs to be included first
 #include <cub/device/device_segmented_sort.cuh>
+#include <cub/util_type.cuh>
 
 #include "catch2_radix_sort_helper.cuh"
 #include "catch2_segmented_sort_helper.cuh"
@@ -37,17 +38,23 @@
 // graph launch.
 // %PARAM% TEST_LAUNCH lid 0:1
 
+static_assert(::cuda::std::__is_extended_floating_point<__half>::value);
+static_assert(::cuda::is_floating_point_v<__half>);
+
+cub::Twiddle<__half>::UnsignedBits a;
+cub::Twiddle<half_t>::UnsignedBits b;
+
 DECLARE_LAUNCH_WRAPPER(cub::DeviceSegmentedSort::StableSortKeys, stable_sort_keys);
 
 using key_types =
   c2h::type_list<bool,
                  std::uint8_t,
                  std::uint64_t
-#if TEST_HALF_T
+#ifdef TEST_HALF_T
                  ,
                  half_t
 #endif
-#if TEST_BF_T
+#ifdef TEST_BF_T
                  ,
                  bfloat16_t
 #endif
diff --git a/cub/test/catch2_test_device_segmented_sort_pairs.cu b/cub/test/catch2_test_device_segmented_sort_pairs.cu
index f24d30dbed1..9ebc2269300 100644
--- a/cub/test/catch2_test_device_segmented_sort_pairs.cu
+++ b/cub/test/catch2_test_device_segmented_sort_pairs.cu
@@ -40,11 +40,11 @@ using pair_types =
   c2h::type_list<c2h::type_list<bool, std::uint8_t>,
                  c2h::type_list<std::int8_t, std::uint64_t>,
                  c2h::type_list<double, float>
-#if TEST_HALF_T
+#ifdef TEST_HALF_T
                  ,
                  c2h::type_list<half_t, std::int8_t>
 #endif
-#if TEST_BF_T
+#ifdef TEST_BF_T
                  ,
                  c2h::type_list<bfloat16_t, float>
 #endif