diff --git a/scripts/internal/winmake.py b/scripts/internal/winmake.py
index 5a80ce90..01b1f201 100755
--- a/scripts/internal/winmake.py
+++ b/scripts/internal/winmake.py
@@ -29,9 +29,11 @@
 
 APPVEYOR = bool(os.environ.get('APPVEYOR'))
 PYTHON = sys.executable if APPVEYOR else os.getenv('PYTHON', sys.executable)
-PYTEST_ARGS = "-v --tb=native -o "
 GET_PIP_URL = "https://bootstrap.pypa.io/get-pip.py"
 PY3 = sys.version_info[0] >= 3
+PYTEST_ARGS = "-v --tb=native "
+if PY3:
+    PYTEST_ARGS += "-o "
 HERE = os.path.abspath(os.path.dirname(__file__))
 ROOT_DIR = os.path.realpath(os.path.join(HERE, "..", ".."))
 PYPY = '__pypy__' in sys.builtin_module_names