Singular form just like the other error message.

diff --git a/Modules/_pickle.c b/Modules/_pickle.c
index 195ee5d7907929a00f1a4d2f118c61bd598f490c..0252c623398a7724f0aca00575c0a79cf94af8d8 100644 (file)
--- a/Modules/_pickle.c
+++ b/Modules/_pickle.c
@@ -5933,7 +5933,7 @@ Unpickler_set_memo(UnpicklerObject *self, PyObject *obj)
                 goto error;
             if (idx < 0) {
                 PyErr_SetString(PyExc_ValueError,
-                                "memos key must be positive integers.");
+                                "memo key must be positive integers.");
                 goto error;
             }
             if (_Unpickler_MemoPut(self, idx, value) < 0)