diff --git a/_pytest/fixtures.py b/_pytest/fixtures.py
index c5da9f4cf43..5dc1aebcc22 100644
--- a/_pytest/fixtures.py
+++ b/_pytest/fixtures.py
@@ -27,10 +27,12 @@
 
 def pytest_sessionstart(session):
     import _pytest.python
+
     scopename2class.update({
         'class': _pytest.python.Class,
         'module': _pytest.python.Module,
         'function': _pytest.main.Item,
+        'session': _pytest.main.Session,
     })
     session._fixturemanager = FixtureManager(session)
 
@@ -62,8 +64,6 @@ def provide(self):
 def get_scope_node(node, scope):
     cls = scopename2class.get(scope)
     if cls is None:
-        if scope == "session":
-            return node.session
         raise ValueError("unknown scope")
     return node.getparent(cls)
 
diff --git a/changelog/2910.trivial b/changelog/2910.trivial
new file mode 100644
index 00000000000..87bf00dfee5
--- /dev/null
+++ b/changelog/2910.trivial
@@ -0,0 +1 @@
+Internal refactoring to simplify scope node lookup.