diff --git a/sbol2/property.py b/sbol2/property.py
index e5536e6..5674c83 100644
--- a/sbol2/property.py
+++ b/sbol2/property.py
@@ -935,9 +935,8 @@ def __init__(self, property_owner, type_uri, reference_type_uri,
         super().__init__(property_owner, type_uri, lower_bound, upper_bound,
                          validation_rules, initial_value)
         self.reference_type_uri = reference_type_uri
-        if self._sbol_owner is None:
-            property_store = []
-            self._sbol_owner.properties[type_uri] = property_store
+        property_store = []
+        self._sbol_owner.properties[type_uri] = property_store
 
     def get(self, item):
         """Return reference object at this index.
diff --git a/test/test_participation.py b/test/test_participation.py
index 3ad5625..6d68715 100644
--- a/test/test_participation.py
+++ b/test/test_participation.py
@@ -17,7 +17,6 @@ def test_add_remove_role(self):
         self.assertEqual([sbol2.SO_PROMOTER, sbol2.SO_CDS], p.roles)
 
     def test_init_with_participant(self):
-
         p = sbol2.Participation('p', participant='p1')
         self.assertEqual('p1', p.participant)
 
diff --git a/test/test_style.py b/test/test_style.py
index bf687ed..1999f0a 100644
--- a/test/test_style.py
+++ b/test/test_style.py
@@ -49,7 +49,7 @@ def test_wildcard_imports(self):
                     if 'import' in line:
                         if '*' in line and 'constants' not in line:
                             msg = 'Wildcard import in {}: {}'
-                            msg = msg.format(f, line)
+                            _ = msg.format(f, line)
                             # self.fail(msg)
                             # print(msg)
                             wildcard_count += 1