diff --git a/src/OpenMesh/Core/IO/reader/OMReader.cc b/src/OpenMesh/Core/IO/reader/OMReader.cc
index 16249362..22c08441 100644
--- a/src/OpenMesh/Core/IO/reader/OMReader.cc
+++ b/src/OpenMesh/Core/IO/reader/OMReader.cc
@@ -521,7 +521,7 @@ size_t _OMReader_::restore_binary_custom_data(std::istream& _is, BaseProperty* _
   Chunk::esize_t block_size;
   Chunk::PropertyName custom_prop;
 
-  bytes += binary<Chunk::esize_t>::restore(_is, block_size, _swap);
+  bytes += restore(_is, block_size, OMFormat::Chunk::Integer_32, _swap);
 
   if (_bp) {
     size_t n_bytes = _bp->size_of(_n_elem);
diff --git a/src/OpenMesh/Core/IO/writer/OMWriter.cc b/src/OpenMesh/Core/IO/writer/OMWriter.cc
index cc38512e..903d63fd 100644
--- a/src/OpenMesh/Core/IO/writer/OMWriter.cc
+++ b/src/OpenMesh/Core/IO/writer/OMWriter.cc
@@ -474,7 +474,7 @@ size_t _OMWriter_::store_binary_custom_chunk(std::ostream& _os,
   bytes += store( _os, OMFormat::Chunk::PropertyName(_bp.name()), _swap );
 
   // 3. block size
-  bytes += store( _os, _bp.size_of(), _swap );
+  bytes += store( _os, _bp.size_of(), OMFormat::Chunk::Integer_32, _swap );
   omlog() << "  n_bytes = " << _bp.size_of() << std::endl;
 
   // 4. data