diff --git a/testing/resources/duplicate_key_json.json b/testing/resources/duplicate_key_json.notjson
similarity index 100%
rename from testing/resources/duplicate_key_json.json
rename to testing/resources/duplicate_key_json.notjson
diff --git a/tests/check_json_test.py b/tests/check_json_test.py
index e010faaa..3ec67f1c 100644
--- a/tests/check_json_test.py
+++ b/tests/check_json_test.py
@@ -9,7 +9,7 @@
         ('bad_json.notjson', 1),
         ('bad_json_latin1.nonjson', 1),
         ('ok_json.json', 0),
-        ('duplicate_key_json.json', 1),
+        ('duplicate_key_json.notjson', 1),
     ),
 )
 def test_main(capsys, filename, expected_retval):