diff --git a/Include/unicodeobject.h b/Include/unicodeobject.h
index d7c9fa7..1b6d1c9 100644
--- a/Include/unicodeobject.h
+++ b/Include/unicodeobject.h
@@ -225,6 +225,7 @@
          * compact = 1
          * ready = 1
          * ascii = 0
+         * utf8 != data
 
        - string created by the legacy API (not ready):
 
@@ -246,6 +247,7 @@
          * compact = 0
          * ready = 1
          * data.any is not NULL
+         * utf8 = data if ascii is 1
 
        String created by the legacy API becomes ready when calling
        PyUnicode_READY().