diff --git a/tests/test_fftfreq.cpp b/tests/test_fftfreq.cpp
index 812f959..5c3046c 100644
--- a/tests/test_fftfreq.cpp
+++ b/tests/test_fftfreq.cpp
@@ -1,118 +1,120 @@
 /*
  *  SPDX-License-Indentifier: AGPL-3.0-or-later
  *
  *  Copyright (©) 2016-2023 EPFL (École Polytechnique Fédérale de Lausanne),
  *  Laboratory (LSMS - Laboratoire de Simulation en Mécanique des Solides)
  *  Copyright (©) 2020-2023 Lucas Frérot
  *
  *  This program is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU Affero General Public License as published
  *  by the Free Software Foundation, either version 3 of the License, or
  *  (at your option) any later version.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU Affero General Public License for more details.
  *
  *  You should have received a copy of the GNU Affero General Public License
  *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
  *
  */
 /* -------------------------------------------------------------------------- */
 #include "fft_engine.hh"
 #include "grid.hh"
 #include "grid_hermitian.hh"
 #include "grid_view.hh"
 #include "mpi_interface.hh"
 #include "partitioner.hh"
 #include "test.hh"
 
 #include <pybind11/embed.h>
 #include <pybind11/numpy.h>
 #include <pybind11/pybind11.h>
 
 using namespace tamaas;
 namespace py = pybind11;
 
 /* -------------------------------------------------------------------------- */
 TEST(TestFFTEngine, Frequencies1D) {
   mpi::sequential_guard guard{};
 
   std::array<UInt, 1> sizes{10};
 
   auto freq{FFTEngine::computeFrequencies<Real, 1, false>(sizes)};
 
   py::module fftfreq{py::module::import("fftfreq")};
 
   std::vector<Real> reference(freq.dataSize());
   py::array py_arg{static_cast<py::ssize_t>(reference.size()), reference.data(),
                    py::none()};
 
   fftfreq.attr("frequencies1D")(py_arg);
 
   EXPECT_TRUE(compare(reference, freq, AreFloatEqual()))
       << "Non hermitian frequencies are wrong";
 
   auto hfreq{FFTEngine::computeFrequencies<Real, 1, true>(sizes)};
   std::iota(reference.begin(), reference.end(), 0);
 
   EXPECT_TRUE(compare(reference, hfreq, AreFloatEqual()))
       << "Hermitian frequencies are wrong";
 }
 
 /* -------------------------------------------------------------------------- */
 TEST(TestFFTEngine, Frequencies2D) {
   std::array<UInt, 2> sizes{10, 10};
   auto global_sizes = Partitioner<2>::global_size(sizes);
 
   auto freq{FFTEngine::computeFrequencies<Real, 2, false>(sizes)};
   auto hfreq{FFTEngine::computeFrequencies<Real, 2, true>(sizes)};
   auto gathered{Partitioner<2>::gather(freq)};
   auto hgathered{Partitioner<2>::gather(hfreq)};
 
   if (mpi::rank() != 0)
     return;
 
   py::module fftfreq{py::module::import("fftfreq")};
 
   std::vector<Real> reference(gathered.dataSize());
-  py::array py_arg{
-      {global_sizes[0], global_sizes[1], 2u}, reference.data(), py::none()};
+  py::array py_arg{{static_cast<py::ssize_t>(global_sizes[0]),
+                    static_cast<py::ssize_t>(global_sizes[1]), py::ssize_t{2}},
+                   reference.data(),
+                   py::none()};
 
   fftfreq.attr("frequencies2D")(py_arg);
   EXPECT_TRUE(compare(reference, gathered, AreFloatEqual()))
       << "Non hermitian frequencies are wrong";
 
   fftfreq.attr("hfrequencies2D")(py_arg);
   EXPECT_TRUE(compare(reference, hgathered, AreFloatEqual()))
       << "Hermitian frequencies are wrong";
 }
 
 /* -------------------------------------------------------------------------- */
 TEST(TestFFTEngine, RealComponents) {
   mpi::sequential_guard guard;
 
   auto even_even{FFTEngine::realCoefficients<2>({{10, 10}})};
   auto even_odd{FFTEngine::realCoefficients<2>({{10, 11}})};
   auto odd_even{FFTEngine::realCoefficients<2>({{11, 10}})};
   auto odd_odd{FFTEngine::realCoefficients<2>({{11, 11}})};
 
   std::vector<UInt> even_even_ref{0, 0, 5, 0, 0, 5, 5, 5};
   std::vector<UInt> even_odd_ref{0, 0, 5, 0};
   std::vector<UInt> odd_even_ref{0, 0, 0, 5};
   std::vector<UInt> odd_odd_ref{0, 0};
 
   auto flatten = [](auto v) {
     std::vector<UInt> flat;
     for (auto&& tuple : v)
       for (auto i : tuple)
         flat.push_back(i);
     return flat;
   };
 
   compare(flatten(even_even), even_even_ref);
   compare(flatten(even_odd), even_odd_ref);
   compare(flatten(odd_even), odd_even_ref);
   compare(flatten(odd_odd), odd_odd_ref);
 }