diff --git a/_pytest/config.py b/_pytest/config.py
index a458e957383..9a308df2bb9 100644
--- a/_pytest/config.py
+++ b/_pytest/config.py
@@ -104,7 +104,7 @@ def _prepareconfig(args=None, plugins=None):
     elif not isinstance(args, (tuple, list)):
         if not isinstance(args, str):
             raise ValueError("not a string or argument list: %r" % (args,))
-        args = shlex.split(args, posix=sys.platform == "win32")
+        args = shlex.split(args, posix=sys.platform != "win32")
     config = get_config()
     pluginmanager = config.pluginmanager
     try: