diff -r 5733529b297c Modules/readline.c
--- a/Modules/readline.c	Tue Oct 09 11:16:33 2012 -0400
+++ b/Modules/readline.c	Tue Oct 09 23:08:18 2012 +0300
@@ -873,8 +873,12 @@
 #endif
     Py_XDECREF(begidx);
     Py_XDECREF(endidx);
-    begidx = PyLong_FromLong((long) start);
-    endidx = PyLong_FromLong((long) end);
+    char *s = strdup(rl_line_buffer);
+    s[end] = 0;
+    endidx = PyLong_FromLong((long) mbstowcs(NULL, s, 0));
+    s[start] = 0;
+    begidx = PyLong_FromLong((long) mbstowcs(NULL, s, 0));
+    free(s);
     return completion_matches(text, *on_completion);
 }