--- Orig/fcntlmodule.c	2003-06-29 20:54:04.000000000 -0500
+++ fcntlmodule.c	2006-02-16 16:11:23.000000000 -0600
@@ -157,12 +157,13 @@
 	PyErr_Clear();
 	if (PyArg_ParseTuple(args, "O&is#:ioctl",
                              conv_descriptor, &fd, &code, &str, &len)) {
-		if (len > sizeof buf) {
+		if (len > (sizeof buf - 1)) {
 			PyErr_SetString(PyExc_ValueError,
 					"ioctl string arg too long");
 			return NULL;
 		}
 		memcpy(buf, str, len);
+		buf[len] = '\0';
 		Py_BEGIN_ALLOW_THREADS
 		ret = ioctl(fd, code, buf);
 		Py_END_ALLOW_THREADS