diff --git a/Lib/test/test_mmap.py b/Lib/test/test_mmap.py
index 2e2ac147968dd4a..5b35688b159dd27 100644
--- a/Lib/test/test_mmap.py
+++ b/Lib/test/test_mmap.py
@@ -1175,8 +1175,8 @@ def test_flush_parameters(self):
             if hasattr(mmap, 'MS_INVALIDATE'):
                 m.flush(PAGESIZE * 2, flags=mmap.MS_INVALIDATE)
             if hasattr(mmap, 'MS_ASYNC') and hasattr(mmap, 'MS_INVALIDATE'):
-                if sys.platform == 'freebsd':
-                    # FreeBSD doesn't support this combination
+                if sys.platform.startswith(('freebsd', 'dragonfly')):
+                    # FreeBSD and DragonFly don't support this combination
                     with self.assertRaises(OSError) as cm:
                         m.flush(0, PAGESIZE, flags=mmap.MS_ASYNC | mmap.MS_INVALIDATE)
                     self.assertEqual(cm.exception.errno, errno.EINVAL)