diff --git a/Include/unicodeobject.h b/Include/unicodeobject.h
index 3e9919f..a2c07f5 100644
--- a/Include/unicodeobject.h
+++ b/Include/unicodeobject.h
@@ -456,7 +456,7 @@
 #define PyUnicode_READY(op)                        \
     (assert(PyUnicode_Check(op)),                       \
      (PyUnicode_IS_READY(op) ?                          \
-      0 : _PyUnicode_Ready((PyUnicodeObject *)(op))))
+      0 : _PyUnicode_Ready((PyObject *)(op))))
 
 /* Return a maximum character value which is suitable for creating another
    string based on op.  This is always an approximation but more efficient
@@ -497,14 +497,16 @@
     );
 #endif
 
-/* Initializes the canonical string representation from a the deprected
-   wstr/Py_UNICODE representation.  This function is used to convert
-   unicode objects which were created using the old API to the new flexible
-   format introduced with PEP 393.  The PyUnicode_READY() macro can be
-   more efficient if the string is already ready. */
+/* Initializes the canonical string representation from a the deprecated
+   wstr/Py_UNICODE representation. This function is used to convert Unicode
+   objects which were created using the old API to the new flexible format
+   introduced with PEP 393.
+
+   Don't call this function directly, use the public PyUnicode_READY() macro
+   instead. */
 #ifndef Py_LIMITED_API
 PyAPI_FUNC(int) _PyUnicode_Ready(
-    PyUnicodeObject *unicode    /* Unicode object */
+    PyObject *unicode           /* Unicode object */
     );
 #endif