--- a/testing/web-platform/harness/wptrunner/executors/pytestrunner/fixtures.py
+++ b/testing/web-platform/harness/wptrunner/executors/pytestrunner/fixtures.py
@@ -53,17 +53,17 @@ class Session(object):
     When the test function goes out of scope, any remaining user prompts
     and opened windows are closed, and the current browsing context is
     switched back to the top-level browsing context.
     """
 
     def __init__(self, client):
         self.client = client
 
-    @pytest.fixture(scope="function")
+    @pytest.fixture(scope="module")
     def session(self, request):
         # finalisers are popped off a stack,
         # making their ordering reverse
         request.addfinalizer(self.switch_to_top_level_browsing_context)
         request.addfinalizer(self.restore_windows)
         request.addfinalizer(self.dismiss_user_prompts)
 
         return self.client