diff --git a/tests/conftest.py b/tests/conftest.py
index 924036b..b7feae4 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -28,6 +28,10 @@ def pytest_addoption(parser):
 
 def pytest_configure(config):
     backend = config.option.spawn_backend
+
+    if plaform.system() == "Windows":
+        backend = 'mp'
+
     if backend == 'mp':
         tractor._spawn.try_set_start_method('spawn')
     elif backend == 'trio_run_in_process':