Index: Lib/test/test_multibytecodec.py
===================================================================
--- Lib/test/test_multibytecodec.py	(révision 68854)
+++ Lib/test/test_multibytecodec.py	(copie de travail)
@@ -44,7 +44,7 @@
         myreplace  = lambda exc: ('', sys.maxsize+1)
         codecs.register_error('test.cjktest', myreplace)
         self.assertRaises(IndexError, dec,
-                          'apple\x92ham\x93spam', 'test.cjktest')
+                          b'apple\x92ham\x93spam', 'test.cjktest')
 
     def test_codingspec(self):
         try:
@@ -61,6 +61,10 @@
         self.assertRaises(AttributeError,
                           _multibytecodec.MultibyteStreamWriter, None)
 
+    def test_decode_unicode(self):
+        # Trying to decode an unicode string should raise a TypeError
+        for enc in ALL_CJKENCODINGS:
+            self.assertRaises(TypeError, codecs.getdecoder(enc), "")
 
 class Test_IncrementalEncoder(unittest.TestCase):
 
@@ -146,6 +150,12 @@
         self.assertRaises(UnicodeDecodeError, decoder.decode, b'', True)
         self.assertEqual(decoder.decode(b'B@$'), '\u4e16')
 
+    def test_decode_unicode(self):
+        # Trying to decode an unicode string should raise a TypeError
+        for enc in ALL_CJKENCODINGS:
+            decoder = codecs.getincrementaldecoder(enc)()
+            self.assertRaises(TypeError, decoder.decode, "")
+
 class Test_StreamReader(unittest.TestCase):
     def test_bug1728403(self):
         try:
Index: Modules/cjkcodecs/multibytecodec.c
===================================================================
--- Modules/cjkcodecs/multibytecodec.c	(révision 68854)
+++ Modules/cjkcodecs/multibytecodec.c	(copie de travail)
@@ -612,7 +612,7 @@
 	const char *data, *errors = NULL;
 	Py_ssize_t datalen, finalsize;
 
-	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s*|z:decode",
+	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "y*|z:decode",
 				codeckwarglist, &pdata, &errors))
 		return NULL;
 	data = pdata.buf;
@@ -1038,7 +1038,7 @@
 	Py_ssize_t wsize, finalsize = 0, size, origpending;
 	int final = 0;
 
-	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s*|i:decode",
+	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "y*|i:decode",
 			incrementalkwarglist, &pdata, &final))
 		return NULL;
 	data = pdata.buf;