diff --git a/cpp/particles/particles_output_hdf5.hpp b/cpp/particles/particles_output_hdf5.hpp
index 6be651799f1bf98e3215cc3b0988b77975706b19..6978a45c351bdb0b80e844dbb4e4fd7832390cc4 100644
--- a/cpp/particles/particles_output_hdf5.hpp
+++ b/cpp/particles/particles_output_hdf5.hpp
@@ -287,7 +287,7 @@ public:
             assert(size_particle_rhs >= 0);
             std::vector<hsize_t> datacount = std::vector<hsize_t>(this->particle_file_layout);
             datacount.insert(datacount.begin(), hsize_t(Parent::getNbRhs()));
-            datacount.push_back(size_particle_positions);
+            datacount.push_back(size_particle_rhs);
             hid_t dataspace = H5Screate_simple(datacount.size(), &datacount.front(), NULL);
             assert(dataspace >= 0);
 
diff --git a/cpp/particles/particles_output_sampling_hdf5.hpp b/cpp/particles/particles_output_sampling_hdf5.hpp
index ea3c94dcec25572dd324c643d9cc80468ba51680..32ef18d3c35e3970ae6719c34837cdb80964d773 100644
--- a/cpp/particles/particles_output_sampling_hdf5.hpp
+++ b/cpp/particles/particles_output_sampling_hdf5.hpp
@@ -218,7 +218,7 @@ public:
         {
             assert(size_particle_rhs >= 0);
             std::vector<hsize_t> datacount = std::vector<hsize_t>(this->particle_file_layout);
-            datacount.push_back(size_particle_positions);
+            datacount.push_back(size_particle_rhs);
             hid_t dataspace = H5Screate_simple(datacount.size(), &datacount.front(), NULL);
             assert(dataspace >= 0);