diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 3f70af7..f5f1c46 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -4832,7 +4832,7 @@
     if (maxchar < 128 && size == unicode_size) {
         if (consumed)
             *consumed = size;
-        return unicode_fromascii(s, size);
+        return unicode_fromascii((const unsigned char *)s, size);
     }
 
     unicode = PyUnicode_New(unicode_size, maxchar);