diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -47,6 +47,7 @@
 
 import argparse
 import collections
+import contextlib
 import difflib
 import distutils.version as version
 import errno
@@ -255,7 +256,7 @@
     else:
         family = socket.AF_INET
     try:
-        with socket.socket(family, socket.SOCK_STREAM) as s:
+        with contextlib.closing(socket.socket(family, socket.SOCK_STREAM)) as s:
             s.bind(('localhost', port))
         return True
     except socket.error as exc: