diff --git a/test/json/schema.py.in b/test/json/schema.py.in
index 7fd4f2fc..5ff9af9f 100755
--- a/test/json/schema.py.in
+++ b/test/json/schema.py.in
@@ -61,7 +61,7 @@ def test_good(schema:str, dir:str) -> int:
             # a two stage check:
             # * apply the schema to the test file
             # * test it matches the truth file
-            with tempfile.NamedTemporaryFile(delete=False) as out:
+            with tempfile.NamedTemporaryFile(delete=True) as out:
                 subprocess.check_call([validate, schema, test], stdout=out)
                 subprocess.check_call([compare, out.name, truth])
                 success = True