diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index fe0a6b8..d6c4bae 100644
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -36,6 +36,21 @@
 
 unsigned int nfs_callback_set_tcpport;
 unsigned short nfs_callback_tcpport;
+static const int nfs_set_port_min = 0;
+static const int nfs_set_port_max = 65535;
+
+static int param_set_port(const char *val, struct kernel_param *kp)
+{
+	char *endp;
+	int num = simple_strtol(val, &endp, 0);
+	if (endp == val || *endp || num < nfs_set_port_min || num > nfs_set_port_max)
+		return -EINVAL;
+	*((int *)kp->arg) = num;
+	return 0;
+}
+
+module_param_call(callback_tcpport, param_set_port, param_get_int,
+		 &nfs_callback_set_tcpport, 0644);
 
 /*
  * This is the callback kernel thread.