diff --git a/tests/extmod/uzlib_decompio_gz.py b/tests/extmod/uzlib_decompio_gz.py
new file mode 100644
index 0000000000..c7aac04e8e
--- /dev/null
+++ b/tests/extmod/uzlib_decompio_gz.py
@@ -0,0 +1,39 @@
+try:
+    import zlib
+except ImportError:
+    import uzlib as zlib
+import uio as io
+
+
+# gzip bitstream
+buf = io.BytesIO(b'\x1f\x8b\x08\x08\x99\x0c\xe5W\x00\x03hello\x00\xcbH\xcd\xc9\xc9\x07\x00\x86\xa6\x106\x05\x00\x00\x00')
+inp = zlib.DecompIO(buf, 16 + 8)
+print(buf.seek(0, 1))
+print(inp.read(1))
+print(buf.seek(0, 1))
+print(inp.read(2))
+print(inp.read())
+print(buf.seek(0, 1))
+print(inp.read(1))
+print(inp.read())
+print(buf.seek(0, 1))
+
+# broken header
+buf = io.BytesIO(b'\x1f\x8c\x08\x08\x99\x0c\xe5W\x00\x03hello\x00\xcbH\xcd\xc9\xc9\x07\x00\x86\xa6\x106\x05\x00\x00\x00')
+try:
+    inp = zlib.DecompIO(buf, 16 + 8)
+except ValueError:
+    print("ValueError")
+
+# broken crc32
+buf = io.BytesIO(b'\x1f\x8b\x08\x08\x99\x0c\xe5W\x00\x03hello\x00\xcbH\xcd\xc9\xc9\x07\x00\x86\xa7\x106\x05\x00\x00\x00')
+inp = zlib.DecompIO(buf, 16 + 8)
+try:
+    inp.read(6)
+except OSError as e:
+    print(repr(e))
+
+# broken uncompressed size - not checked so far
+#buf = io.BytesIO(b'\x1f\x8b\x08\x08\x99\x0c\xe5W\x00\x03hello\x00\xcbH\xcd\xc9\xc9\x07\x00\x86\xa6\x106\x06\x00\x00\x00')
+#inp = zlib.DecompIO(buf, 16 + 8)
+#inp.read(6)
diff --git a/tests/extmod/uzlib_decompio_gz.py.exp b/tests/extmod/uzlib_decompio_gz.py.exp
new file mode 100644
index 0000000000..2330580f8c
--- /dev/null
+++ b/tests/extmod/uzlib_decompio_gz.py.exp
@@ -0,0 +1,11 @@
+16
+b'h'
+18
+b'el'
+b'lo'
+31
+b''
+b''
+31
+ValueError
+OSError(22,)