diff --git a/Python/ast.c b/Python/ast.c
index 0f23f67..1a4a311 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -4588,7 +4588,7 @@
         if (*s & 0x80) { /* XXX inefficient */
             PyObject *w;
             int kind;
-            void *data;
+            const void *data;
             Py_ssize_t len, i;
             w = decode_utf8(c, &s, end);
             if (w == NULL) {