diff --git a/openmc/filter.py b/openmc/filter.py
index f5268ad81..432ea1599 100644
--- a/openmc/filter.py
+++ b/openmc/filter.py
@@ -1959,9 +1959,9 @@ class EnergyFunctionFilter(Filter):
         filter_id = int(group.name.split('/')[-1].lstrip('filter '))
 
         out = cls(energy, y, filter_id=filter_id)
-        if 'interpolation' in group.attrs:
+        if 'interpolation' in group:
             out.interpolation =  \
-                openmc.data.INTERPOLATION_SCHEME[group.attrs['interpolation']]
+                openmc.data.INTERPOLATION_SCHEME[group['interpolation'][()]]
 
         return out
 
diff --git a/src/tallies/filter_energyfunc.cpp b/src/tallies/filter_energyfunc.cpp
index 819b5d13e..fb76fb215 100644
--- a/src/tallies/filter_energyfunc.cpp
+++ b/src/tallies/filter_energyfunc.cpp
@@ -29,6 +29,16 @@ void EnergyFunctionFilter::from_xml(pugi::xml_node node)
   interpolation_ = Interpolation::lin_lin;
   if (check_for_node(node, "interpolation")) {
     std::string interpolation = get_node_value(node, "interpolation");
+    if (interpolation == "linear-linear") {
+      interpolation_ = Interpolation::lin_lin;
+    } else if (interpolation == "log-log") {
+      interpolation_ = Interpolation::log_log;
+    } else {
+      fatal_error(fmt::format(
+        "Invalid interpolation type '{}' specified on EnergyFunctionFilter {}. "
+        "Must be 'linear-linear' or 'log-log'.",
+        interpolation, id()));
+    }
   }
 
   this->set_data(energy, y);
@@ -90,7 +100,7 @@ void EnergyFunctionFilter::to_statepoint(hid_t filter_group) const
   Filter::to_statepoint(filter_group);
   write_dataset(filter_group, "energy", energy_);
   write_dataset(filter_group, "y", y_);
-  write_attribute<int>(
+  write_dataset(
     filter_group, "interpolation", static_cast<int>(interpolation_));
 }
 
diff --git a/tests/regression_tests/filter_energyfun/test.py b/tests/regression_tests/filter_energyfun/test.py
index cb658b902..e0a191ce8 100644
--- a/tests/regression_tests/filter_energyfun/test.py
+++ b/tests/regression_tests/filter_energyfun/test.py
@@ -52,8 +52,6 @@ def model():
     tallies[2].filters = [filt3]
     model.tallies.extend(tallies)
 
-
-
     return model
 
 
@@ -74,15 +72,15 @@ class FilterEnergyFunHarness(PyAPITestHarness):
         # Read the statepoint file.
         sp = openmc.StatePoint(self._sp_name)
 
-        # check that values are round-tripped correctly from
+        # check that information is round-tripped correctly from
         # the statepoint file
-        sp_tally = sp.get_tally(id=2)
+        sp_tally = sp.get_tally(id=3)
         sp_filt = sp_tally.find_filter(openmc.EnergyFunctionFilter)
 
-        model_tally = self._model.tallies[1]
+        model_tally = self._model.tallies[2]
         model_filt = model_tally.find_filter(openmc.EnergyFunctionFilter)
 
-        assert sp_filt.interpolation == 'linear-linear'
+        assert sp_filt.interpolation == 'log-log'
         assert all(sp_filt.energy == model_filt.energy)
         assert all(sp_filt.y == model_filt.y)