Use os.fsencode() to support surrogates
diff --git a/Demo/zlib/minigzip.py b/Demo/zlib/minigzip.py
index 52e81b9..b57de73 100755
--- a/Demo/zlib/minigzip.py
+++ b/Demo/zlib/minigzip.py
@@ -31,7 +31,7 @@
     write32(output, mtime)
     output.write(b'\002')                # ... slowest compression alg. ...
     output.write(b'\377')                # ... OS (=unknown) ...
-    bfilename = filename.encode(sys.getfilesystemencoding())
+    bfilename = os.fsencode(filename)
     output.write(bfilename + b'\000')    # ... original filename ...
 
     crcval = zlib.crc32(b'')