diff --git a/tests/extmod/zlibd_decompress.py b/tests/extmod/zlibd_decompress.py
index 041cabdfe1..4d8e44f3ac 100644
--- a/tests/extmod/zlibd_decompress.py
+++ b/tests/extmod/zlibd_decompress.py
@@ -9,6 +9,7 @@ PATTERNS = [
     (b'a', b'x\x9cK\x04\x00\x00b\x00b'),
     (b'0' * 100, b'x\x9c30\xa0=\x00\x00\xb3q\x12\xc1'),
     (bytes(range(64)), b'x\x9cc`dbfaec\xe7\xe0\xe4\xe2\xe6\xe1\xe5\xe3\x17\x10\x14\x12\x16\x11\x15\x13\x97\x90\x94\x92\x96\x91\x95\x93WPTRVQUS\xd7\xd0\xd4\xd2\xd6\xd1\xd5\xd370426153\xb7\xb0\xb4\xb2\xb6\xb1\xb5\xb3\x07\x00\xaa\xe0\x07\xe1'),
+    (b'hello', b'x\x01\x01\x05\x00\xfa\xffhello\x06,\x02\x15'), # compression level 0
 ]
 
 for unpacked, packed in PATTERNS: