diff --git a/hysop/operator/hdf_io.py b/hysop/operator/hdf_io.py
index 769864b369d334a99d556c6aa91c38cd2debc879..26ece61d770be9de535de7b4521e797461665f77 100755
--- a/hysop/operator/hdf_io.py
+++ b/hysop/operator/hdf_io.py
@@ -187,8 +187,8 @@ class HDF_IO(ComputationalGraphOperator):
         super(HDF_IO, self).discretize()
         topo = self.input_fields[sorted(self.input_fields.keys(), key=lambda f:f.name)[0]]
         use_local_hdf5 = (topo.cart_size == 1)
-        use_local_hdf5 |= (topo.proc_shape[0] == topo.cart_size) and (topo.cart_size < 16)
-        # XDMF JOIN do not support more than 16 arguments (16 seems too much)
+        use_local_hdf5 |= (topo.proc_shape[0] == topo.cart_size) and (topo.cart_size <= 16)
+        # XDMF JOIN do not support more than 16 arguments
 
         self.topology = topo
         self.use_local_hdf5 = use_local_hdf5