diff --git a/openmc/data/fission_energy.py b/openmc/data/fission_energy.py
index 5ce9f47d5c..a7cf3dfed3 100644
--- a/openmc/data/fission_energy.py
+++ b/openmc/data/fission_energy.py
@@ -107,7 +107,7 @@ def write_compact_458_library(endf_files, output_name='fission_Q_data.h5',
 
     """
     # Open the output file.
-    out = h5py.File(output_name, 'w', libver='latest')
+    out = h5py.File(output_name, 'w', libver='earliest')
 
     # Write comments, if given.  This commented out comment is the one used for
     # the library distributed with OpenMC.
diff --git a/openmc/data/neutron.py b/openmc/data/neutron.py
index ed2f4f8b75..b0968fdfad 100644
--- a/openmc/data/neutron.py
+++ b/openmc/data/neutron.py
@@ -496,7 +496,7 @@ class IncidentNeutron(EqualityMixin):
                                       'originated from an ENDF file.')
 
         # Open file and write version
-        f = h5py.File(path, mode, libver='latest')
+        f = h5py.File(path, mode, libver='earliest')
         f.attrs['version'] = np.array(HDF5_VERSION)
 
         # Write basic data
diff --git a/openmc/data/thermal.py b/openmc/data/thermal.py
index 6e7b0fe02c..0234839aca 100644
--- a/openmc/data/thermal.py
+++ b/openmc/data/thermal.py
@@ -258,7 +258,7 @@ class ThermalScattering(EqualityMixin):
 
         """
         # Open file and write version
-        f = h5py.File(path, mode, libver='latest')
+        f = h5py.File(path, mode, libver='earliest')
         f.attrs['version'] = np.array(HDF5_VERSION)
 
         # Write basic data
diff --git a/openmc/mgxs/library.py b/openmc/mgxs/library.py
index 3cdd0fbf54..5cbb56c2b5 100644
--- a/openmc/mgxs/library.py
+++ b/openmc/mgxs/library.py
@@ -823,7 +823,7 @@ class Library(object):
         # Add an attribute for the number of energy groups to the HDF5 file
         full_filename = os.path.join(directory, filename)
         full_filename = full_filename.replace(' ', '-')
-        f = h5py.File(full_filename, 'w')
+        f = h5py.File(full_filename, 'w', libver='earliest')
         f.attrs['# groups'] = self.num_groups
         f.close()
 
diff --git a/openmc/mgxs/mgxs.py b/openmc/mgxs/mgxs.py
index 192f484a5e..f9eb0cdd1b 100644
--- a/openmc/mgxs/mgxs.py
+++ b/openmc/mgxs/mgxs.py
@@ -1693,9 +1693,9 @@ class MGXS(object):
         filename = filename.replace(' ', '-')
 
         if append and os.path.isfile(filename):
-            xs_results = h5py.File(filename, 'a')
+            xs_results = h5py.File(filename, 'a', libver='earliest')
         else:
-            xs_results = h5py.File(filename, 'w')
+            xs_results = h5py.File(filename, 'w', libver='earliest')
 
         # Construct a collection of the subdomains to report
         if not isinstance(subdomains, string_types):
diff --git a/openmc/mgxs_library.py b/openmc/mgxs_library.py
index 93a3607d99..1ac5f1468d 100644
--- a/openmc/mgxs_library.py
+++ b/openmc/mgxs_library.py
@@ -2517,7 +2517,7 @@ class MGXSLibrary(object):
         check_type('filename', filename, string_types)
 
         # Create and write to the HDF5 file
-        file = h5py.File(filename, "w")
+        file = h5py.File(filename, "w", libver='earliest')
         file.attrs['filetype'] = np.string_(_FILETYPE_MGXS_LIBRARY)
         file.attrs['version'] = [_VERSION_MGXS_LIBRARY, 0]
         file.attrs['energy_groups'] = self.energy_groups.num_groups