diff -r be66786e95de Python/ast.c
--- a/Python/ast.c	Mon Nov 14 12:38:43 2016 +0100
+++ b/Python/ast.c	Mon Nov 14 18:04:13 2016 +0100
@@ -4129,7 +4129,13 @@ warn_invalid_escape_sequence(struct comp
                                    NULL, NULL) < 0 &&
         PyErr_ExceptionMatches(PyExc_DeprecationWarning))
     {
-        const char *s = PyUnicode_AsUTF8(msg);
+        const char *s;
+
+        /* Replace the DeprecationWarning exception with a SyntaxError
+           to get a more accurate error report */
+        PyErr_Clear();
+
+        s = PyUnicode_AsUTF8(msg);
         if (s != NULL) {
             ast_error(c, n, s);
         }