diff --git a/testing/test_plugin.py b/testing/test_plugin.py
index 0406be7..319e2ec 100644
--- a/testing/test_plugin.py
+++ b/testing/test_plugin.py
@@ -20,7 +20,7 @@ def test_dist_options(testdir):
     check_options(config)
     assert config.option.dist == "load"
     assert config.option.tx == ['popen'] * 2
-    config = testdir.parseconfigure("--numprocesses 2")
+    config = testdir.parseconfigure("--numprocesses", "2")
     check_options(config)
     assert config.option.dist == "load"
     assert config.option.tx == ['popen'] * 2