Index: Include/unicodeobject.h
===================================================================
--- Include/unicodeobject.h	(revision 86735)
+++ Include/unicodeobject.h	(working copy)
@@ -355,6 +355,12 @@
     for (i_ = 0; i_ < (length); i_++) t_[i_] = v_;\
     } while (0)
 
+#ifdef Py_UNICODE_WIDE
+#    define Py_UNICODE_NEXT(ptr, end) *ptr++
+#else
+PyAPI_FUNC(Py_UCS4) _Py_unicode_next(const Py_UNICODE **pptr, const Py_UNICODE *end);
+#    define Py_UNICODE_NEXT(ptr, end) _Py_unicode_next(&ptr, end)
+#endif
 /* Check if substring matches at given offset.  The offset must be
    valid, and the substring must not be empty. */
 
@@ -737,7 +743,7 @@
     const char *errors          /* error handling */
     );
 
-/* Encodes a Unicode object and returns the result as Python string
+/* Encodes a Unicode object and returns the result as Python bytes
    object. */
 
 PyAPI_FUNC(PyObject*) PyUnicode_AsEncodedString(
Index: Objects/unicodeobject.c
===================================================================
--- Objects/unicodeobject.c	(revision 86735)
+++ Objects/unicodeobject.c	(working copy)
@@ -7785,7 +7785,7 @@
 static PyObject*
 unicode_isalpha(PyUnicodeObject *self)
 {
-    register const Py_UNICODE *p = PyUnicode_AS_UNICODE(self);
+    const Py_UNICODE *p = PyUnicode_AS_UNICODE(self);
     register const Py_UNICODE *e;
 
     /* Shortcut for single character strings */
@@ -7798,8 +7798,8 @@
         return PyBool_FromLong(0);
 
     e = p + PyUnicode_GET_SIZE(self);
-    for (; p < e; p++) {
-        if (!Py_UNICODE_ISALPHA(*p))
+    while (p < e) {
+        if (!Py_UNICODE_ISALPHA(Py_UNICODE_NEXT(p, e)))
             return PyBool_FromLong(0);
     }
     return PyBool_FromLong(1);
@@ -10364,7 +10364,24 @@
     return PyModule_Create(&_string_module);
 }
 
+#ifndef Py_UNICODE_WIDE
+Py_UCS4
+_Py_unicode_next(const Py_UNICODE **pptr, const Py_UNICODE *end)
+{
+    Py_UCS4 ch;
+    ch = *(*pptr)++;
+    if (0xD800 <= ch && ch <= 0xDBFF && *pptr < end) {
+        Py_UCS4 ch2 = **pptr;
+        if (0xDC00 <= ch2 && ch2 <= 0xDFFF) {
+            ch = (((ch - 0xD800)<<10) | (ch2 - 0xDC00)) + 0x10000;
+            (*pptr)++;
+        }
+    }
+    return ch;
+}
 
+#endif
+
 #ifdef __cplusplus
 }
 #endif