diff --git a/pyftpdlib/test/test_functional.py b/pyftpdlib/test/test_functional.py
index 457f462a..213c8f99 100644
--- a/pyftpdlib/test/test_functional.py
+++ b/pyftpdlib/test/test_functional.py
@@ -49,6 +49,8 @@
 from pyftpdlib.test import safe_rmpath
 from pyftpdlib.test import touch
 
+from . import MProcessTestFTPd
+
 
 class TestFtpAuthentication(PyftpdlibTestCase):
     """Test: USER, PASS, REIN."""
@@ -1914,7 +1916,8 @@ def test_use_gmt_times(self):
 
 
 class TestCallbacks(PyftpdlibTestCase):
-    server_class = ThreadedTestFTPd
+    # using m-proc server since m-thread server produces random failures
+    server_class = MProcessTestFTPd
     client_class = ftplib.FTP
 
     def setUp(self):