diff -r 5115f39cc59f Modules/unicodedata.c
--- a/Modules/unicodedata.c	Sat Dec 19 22:51:00 2015 +0200
+++ b/Modules/unicodedata.c	Sun Dec 20 01:10:53 2015 +0200
@@ -1232,8 +1232,11 @@ unicodedata_UCD_lookup_impl(PyObject *se
 {
     Py_UCS4 code;
     unsigned int index;
-    if (name_length > INT_MAX) {
-        PyErr_SetString(PyExc_KeyError, "name too long");
+    if (name_length >= NAME_MAXLEN) {
+        const char fmt[] = "undefined character name '%%.%ds...'";
+        char buffer[sizeof(fmt) + 20];
+        sprintf(buffer, fmt, (int)NAME_MAXLEN);
+        PyErr_Format(PyExc_KeyError, buffer, name);
         return NULL;
     }