diff --git a/tests/opc/test_phys_pkg.py b/tests/opc/test_phys_pkg.py
index 6de0d868b..d325ae68f 100644
--- a/tests/opc/test_phys_pkg.py
+++ b/tests/opc/test_phys_pkg.py
@@ -58,8 +58,9 @@ def it_returns_none_when_part_has_no_rels_xml(self, dir_reader):
     def pkg_file_(self, request):
         return loose_mock(request)
 
+    @classmethod
     @pytest.fixture(scope="class")
-    def dir_reader(self):
+    def dir_reader(cls):
         return _DirPkgReader(dir_pkg_path)
 
 
@@ -114,8 +115,9 @@ def it_returns_none_when_part_has_no_rels_xml(self, phys_reader):
 
     # fixtures ---------------------------------------------
 
+    @classmethod
     @pytest.fixture(scope="class")
-    def phys_reader(self):
+    def phys_reader(cls):
         phys_reader = _ZipPkgReader(zip_pkg_path)
         yield phys_reader
         phys_reader.close()