diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 60b0a1f..3afb799 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -1985,6 +1985,9 @@
     if (start == end)
         return 127;
 
+    if (PyUnicode_IS_ASCII(unicode))
+        return 127;
+
     kind = PyUnicode_KIND(unicode);
     startptr = PyUnicode_DATA(unicode);
     endptr = (char *)startptr + end * kind;