diff --git a/src/_pytest/mark/structures.py b/src/_pytest/mark/structures.py
index 43556f0a4..053297fa2 100644
--- a/src/_pytest/mark/structures.py
+++ b/src/_pytest/mark/structures.py
@@ -368,11 +368,9 @@ def get_unpacked_marks(obj: object) -> Iterable[Mark]:
     return normalize_mark_list(mark_list)
 
 
-def get_mro_marks(cls: type) -> List[Mark]:
-    if cls is object or cls is None:
-        return []
-    if hasattr(cls, "mro_markers"):
-        return getattr(cls, "mro_markers")
+def get_mro_marks(cls: type):
+    if cls is object or cls is None or hasattr(cls, "mro_markers"):
+        return getattr(cls, "mro_markers", [])
 
     # markers = list(mark for mark in get_unpacked_marks(cls) if mark.name != "parametrize")
     markers = list(mark for mark in get_unpacked_marks(cls))
diff --git a/testing/test_mark.py b/testing/test_mark.py
index 074cc693e..9eecdb59c 100644
--- a/testing/test_mark.py
+++ b/testing/test_mark.py
@@ -1129,8 +1129,8 @@ def test_marker_expr_eval_failure_handling(pytester: Pytester, expr) -> None:
     assert result.ret == ExitCode.USAGE_ERROR
 
 
-def test_markers_from_multiple_inheritances(pytester: Pytester, request) -> None:
-    py_file = pytester.makepyfile(
+def test_markers_from_multiple_inheritances(pytester: Pytester) -> None:
+    pytester.makepyfile(
         """
         import pytest
         @pytest.mark.mark1