diff --git a/lib/spack/spack/test/concretize_preferences.py b/lib/spack/spack/test/concretize_preferences.py
index 813d250646f..4129ed22a5b 100644
--- a/lib/spack/spack/test/concretize_preferences.py
+++ b/lib/spack/spack/test/concretize_preferences.py
@@ -184,7 +184,9 @@ def test_config_set_url_for_package(self, mutable_mock_repo):
         applied correctly
         """
         update_packages(
-            "mpileaks", "package_attributes", {"url": "http://www.somewhereelse.com/mpileaks-1.0.tar.gz"}
+            "mpileaks",
+            "package_attributes",
+            {"url": "http://www.somewhereelse.com/mpileaks-1.0.tar.gz"},
         )
         spec = concretize("mpileaks")
         assert spec.package.fetcher[0].url == "http://www.somewhereelse.com/mpileaks-2.3.tar.gz"