diff --git a/swh/graph/tests/conftest.py b/swh/graph/tests/conftest.py
index 781e5b2..a3af742 100644
--- a/swh/graph/tests/conftest.py
+++ b/swh/graph/tests/conftest.py
@@ -1,51 +1,51 @@
 import multiprocessing
 import pytest
 
 from aiohttp.test_utils import TestServer, TestClient, loop_context
 from pathlib import Path
 
 from swh.graph.graph import load as graph_load
 from swh.graph.client import RemoteGraphClient
 from swh.graph.backend import Backend
 from swh.graph.server.app import make_app
 
 SWH_GRAPH_TESTS_ROOT = Path(__file__).parents[0]
 TEST_GRAPH_PATH = SWH_GRAPH_TESTS_ROOT / 'dataset/output/example'
 
 
 class GraphServerProcess(multiprocessing.Process):
     def __init__(self, q, *args, **kwargs):
         self.q = q
         super().__init__(*args, **kwargs)
 
     def run(self):
         try:
             backend = Backend(graph_path=str(TEST_GRAPH_PATH))
             with backend:
                 with loop_context() as loop:
                     app = make_app(backend=backend, debug=True)
                     client = TestClient(TestServer(app), loop=loop)
                     loop.run_until_complete(client.start_server())
                     url = client.make_url('/graph/')
                     self.q.put(url)
                     loop.run_forever()
         except Exception as e:
             self.q.put(e)
 
 
 @pytest.fixture(scope="module")
 def graph_client():
     queue = multiprocessing.Queue()
     server = GraphServerProcess(queue)
     server.start()
     res = queue.get()
-    if instanceof(res, Exception):
+    if isinstance(res, Exception):
         raise res
     yield RemoteGraphClient(str(res))
     server.terminate()
 
 
 @pytest.fixture(scope="module")
 def graph():
     with graph_load(str(TEST_GRAPH_PATH)) as g:
         yield g