diff --git a/Lib/test/test_fileio.py b/Lib/test/test_fileio.py
index 634a764..2825a87 100644
--- a/Lib/test/test_fileio.py
+++ b/Lib/test/test_fileio.py
@@ -308,7 +308,7 @@
             self.assertEqual(f.writable(), True)
             if sys.platform != "darwin" and \
                'bsd' not in sys.platform and \
-               not sys.platform.startswith('sunos'):
+               not sys.platform.startswith(('sunos', 'aix')):
                 # Somehow /dev/tty appears seekable on some BSDs
                 self.assertEqual(f.seekable(), False)
             self.assertEqual(f.isatty(), True)