diff --git a/src/serial_io.h b/src/serial_io.h
index 5b51b9b41870846c40b8d3d358f31ebfe7202203..02b3a22fa64e0ecef2076de9da77de3e303c325c 100644
--- a/src/serial_io.h
+++ b/src/serial_io.h
@@ -50,13 +50,6 @@ void write_output_serial(struct engine* e, const char* baseName,
                          const struct unit_system* snapshot_units, int mpi_rank,
                          int mpi_size, MPI_Comm comm, MPI_Info info);
 
-void writeArray(const struct engine* e, hid_t grp, char* fileName,
-                FILE* xmfFile, char* partTypeGroupName,
-                const struct io_props props, size_t N, long long N_total,
-                int mpi_rank, long long offset,
-                const struct unit_system* internal_units,
-                const struct unit_system* snapshot_units);
-
 #endif /* HAVE_HDF5 && WITH_MPI && !HAVE_PARALLEL_HDF5 */
 
 #endif /* SWIFT_SERIAL_IO_H */
diff --git a/src/single_io.h b/src/single_io.h
index 591f0ef8be6ed831d5cf2a6d465498cc259286d5..a28b06979fe86bc37ff262e7462cd8eb773bcef7 100644
--- a/src/single_io.h
+++ b/src/single_io.h
@@ -44,12 +44,6 @@ void write_output_single(struct engine* e, const char* baseName,
                          const struct unit_system* internal_units,
                          const struct unit_system* snapshot_units);
 
-void writeArray(const struct engine* e, hid_t grp, char* fileName,
-                FILE* xmfFile, char* partTypeGroupName,
-                const struct io_props props, size_t N,
-                const struct unit_system* internal_units,
-                const struct unit_system* snapshot_units);
-
 #endif /* HAVE_HDF5 && !WITH_MPI */
 
 #endif /* SWIFT_SINGLE_IO_H */