diff --git a/Modules/_csv.c b/Modules/_csv.c
index 88e3e9065842e8..a54e74ecc3ff17 100644
--- a/Modules/_csv.c
+++ b/Modules/_csv.c
@@ -818,7 +818,7 @@ Reader_iternext(ReaderObj *self)
             if (c == '\0') {
                 Py_DECREF(lineobj);
                 PyErr_Format(error_obj,
-                             "line contains NULL byte");
+                             "line contains NUL");
                 goto err;
             }
             if (parse_process_char(self, c) < 0) {