diff --git a/django_db_geventpool/backends/postgresql_psycopg2/psycopg2_pool.py b/django_db_geventpool/backends/postgresql_psycopg2/psycopg2_pool.py
index 13df989..1d8568f 100755
--- a/django_db_geventpool/backends/postgresql_psycopg2/psycopg2_pool.py
+++ b/django_db_geventpool/backends/postgresql_psycopg2/psycopg2_pool.py
@@ -14,10 +14,7 @@
     from gevent.lock import RLock
 except ImportError:
     from eventlet import queue
-    from ...utils import nullcontext
-
-    def RLock():
-        return nullcontext
+    from ...utils import NullContextRLock as RLock
 
 try:
     from psycopg2 import connect, DatabaseError
diff --git a/django_db_geventpool/utils.py b/django_db_geventpool/utils.py
index 555ff9f..d3c4459 100644
--- a/django_db_geventpool/utils.py
+++ b/django_db_geventpool/utils.py
@@ -16,6 +16,12 @@ def wrapper(*args, **kwargs):
     return wrapper
 
 
-@contextmanager
-def nullcontext(enter_result=None):
-    yield enter_result
+class NullContextRLock:
+    def __init__(self, enter_result=None):
+        self._enter_result = enter_result
+
+    def __enter__(self):
+        return self._enter_result
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        return None