diff -r 154ae3af0317 Lib/test/test_codeccallbacks.py
--- a/Lib/test/test_codeccallbacks.py	Fri Jan 09 16:40:38 2015 -0600
+++ b/Lib/test/test_codeccallbacks.py	Sat Jan 10 05:34:19 2015 +0200
@@ -971,6 +971,19 @@
                 with self.assertRaises(TypeError):
                     data.decode(encoding, "test.replacing")
 
+    def test_bug23215(self):
+        # This happens to be invalid for all the encodings in question
+        data = 100 * "\udc00"
+        encs = ("big5", "big5hkscs", "cp932", "cp949", "cp950", "euc_jis_2004",
+                "euc_jisx0213", "euc_jp", "euc_kr", "gb18030", "gb2312", "gbk", "hz",
+                "iso2022_jp", "iso2022_jp_1", "iso2022_jp_2", "iso2022_jp_2004",
+                "iso2022_jp_3", "iso2022_jp_ext", "iso2022_kr", "johab",
+                "shift_jis", "shift_jis_2004", "shift_jisx0213")
+
+        codecs.register_error("test.ignore", codecs.ignore_errors)
+
+        for enc in encs:
+            data.encode(enc, "test.ignore")
 
 if __name__ == "__main__":
     unittest.main()
diff -r 154ae3af0317 Modules/cjkcodecs/multibytecodec.c
--- a/Modules/cjkcodecs/multibytecodec.c	Fri Jan 09 16:40:38 2015 -0600
+++ b/Modules/cjkcodecs/multibytecodec.c	Sat Jan 10 05:34:19 2015 +0200
@@ -324,10 +324,12 @@
 
     assert(PyBytes_Check(retstr));
     retstrsize = PyBytes_GET_SIZE(retstr);
-    REQUIRE_ENCODEBUFFER(buf, retstrsize);
+    if(retstrsize > 0) {
+        REQUIRE_ENCODEBUFFER(buf, retstrsize);
 
-    memcpy(buf->outbuf, PyBytes_AS_STRING(retstr), retstrsize);
-    buf->outbuf += retstrsize;
+        memcpy(buf->outbuf, PyBytes_AS_STRING(retstr), retstrsize);
+        buf->outbuf += retstrsize;
+    }
 
     newpos = PyLong_AsSsize_t(PyTuple_GET_ITEM(retobj, 1));
     if (newpos < 0 && !PyErr_Occurred())