#13406: silence deprecation warnings in test_codecs.
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index cdad738..a0459a0 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -6235,7 +6235,7 @@
     PyObject *exc = NULL;
 
     if (PyErr_WarnEx(PyExc_DeprecationWarning,
-                     "unicode_internal codecs has been deprecated",
+                     "unicode_internal codec has been deprecated",
                      1))
         return NULL;