diff --git a/tests/test_igzip_threaded.py b/tests/test_igzip_threaded.py
index dd26e95e..15d334d7 100644
--- a/tests/test_igzip_threaded.py
+++ b/tests/test_igzip_threaded.py
@@ -224,9 +224,7 @@ def test_close_writer(threads):
     f = igzip_threaded._ThreadedGzipWriter(
         io.BytesIO(), threads=threads)
     f.close()
-    assert f.closed
-    # Make sure double closing does not raise errors
-    f.close()
+    assert_writer_closed(f)
 
 
 def test_reader_not_writable():