diff --git a/_pytest/fixtures.py b/_pytest/fixtures.py
index 621e38057..16481ca1c 100644
--- a/_pytest/fixtures.py
+++ b/_pytest/fixtures.py
@@ -19,6 +19,11 @@ from _pytest.compat import (
 )
 
 def pytest_sessionstart(session):
+    scopename2class.update({
+        'class': pytest.Class,
+        'module': pytest.Module,
+        'function': pytest.Item,
+    })
     session._fixturemanager = FixtureManager(session)
 
 
@@ -45,15 +50,6 @@ def scopeproperty(name=None, doc=None):
     return decoratescope
 
 
-def pytest_namespace():
-    scopename2class.update({
-        'class': pytest.Class,
-        'module': pytest.Module,
-        'function': pytest.Item,
-    })
-    return {}
-
-
 def get_scope_node(node, scope):
     cls = scopename2class.get(scope)
     if cls is None: