diff --git a/pyftpdlib/servers.py b/pyftpdlib/servers.py
index e703af3f..ab6dba73 100644
--- a/pyftpdlib/servers.py
+++ b/pyftpdlib/servers.py
@@ -515,6 +515,8 @@ def _map_len(self):
 if os.name == 'posix':
     try:
         import multiprocessing
+        multiprocessing.Lock()
+        multiprocessing.Event()
     except ImportError:
         pass
     else: