diff --git a/CONTRIBUTORS b/CONTRIBUTORS
new file mode 100644
--- /dev/null
+++ b/CONTRIBUTORS
@@ -0,0 +1 @@
+Thibault Allançon
diff --git a/swh/core/api/tests/server_testing.py b/swh/core/api/tests/server_testing.py
--- a/swh/core/api/tests/server_testing.py
+++ b/swh/core/api/tests/server_testing.py
@@ -6,11 +6,11 @@
 import abc
 import multiprocessing
 import os
-import socket
 import time
 from urllib.request import urlopen
 
 import aiohttp
+import aiohttp.test_utils
 
 
 class ServerTestFixtureBaseClass(metaclass=abc.ABCMeta):
@@ -63,12 +63,7 @@
         self.process = None
 
         self.process_config()
-
-        # Get an available port number
-        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-        sock.bind(('127.0.0.1', 0))
-        self.port = sock.getsockname()[1]
-        sock.close()
+        self.port = aiohttp.test_utils.unused_port()
 
         worker_fn = self.define_worker_function()