diff --git a/jsonschema/tests/test_cli.py b/jsonschema/tests/test_cli.py
index 22528feb5..884a037ab 100644
--- a/jsonschema/tests/test_cli.py
+++ b/jsonschema/tests/test_cli.py
@@ -747,7 +747,7 @@ def test_nonexistent_file_with_explicit_base_uri(self):
                 ],
             )
         error = str(e.exception)
-        self.assertIn("/someNonexistentFile.json'", error)
+        self.assertIn(f"{os.sep}someNonexistentFile.json'", error)
 
     def test_invalid_exlicit_base_uri(self):
         schema = '{"$ref": "foo.json#definitions/num"}'