diff --git a/Python/getargs.c b/Python/getargs.c
index 8839492..936eb6a 100644
--- a/Python/getargs.c
+++ b/Python/getargs.c
@@ -1014,7 +1014,10 @@ convertsimple(PyObject *arg, const char **p_format, va_list *p_va, int flags,
     case 'u': /* raw unicode buffer (Py_UNICODE *) */
     case 'Z': /* raw unicode buffer or None */
     {
-        // TODO: Raise DeprecationWarning
+        if (PyErr_WarnFormat(PyExc_DeprecationWarning, 1,
+                "getargs: The '%c' format is deprecated. Use 'U' instead.", c)) {
+            return NULL;
+        }
 _Py_COMP_DIAG_PUSH
 _Py_COMP_DIAG_IGNORE_DEPR_DECLS
         Py_UNICODE **p = va_arg(*p_va, Py_UNICODE **);