diff --git a/tests/opc/test_phys_pkg.py b/tests/opc/test_phys_pkg.py
index 6de0d868b..c4fef38f2 100644
--- a/tests/opc/test_phys_pkg.py
+++ b/tests/opc/test_phys_pkg.py
@@ -59,7 +59,8 @@ def pkg_file_(self, request):
         return loose_mock(request)
 
     @pytest.fixture(scope="class")
-    def dir_reader(self):
+    @classmethod
+    def dir_reader(cls):
         return _DirPkgReader(dir_pkg_path)
 
 
@@ -115,7 +116,8 @@ def it_returns_none_when_part_has_no_rels_xml(self, phys_reader):
     # fixtures ---------------------------------------------
 
     @pytest.fixture(scope="class")
-    def phys_reader(self):
+    @classmethod
+    def phys_reader(cls):
         phys_reader = _ZipPkgReader(zip_pkg_path)
         yield phys_reader
         phys_reader.close()