diff --git a/drivers/watchdog/imxwd.c b/drivers/watchdog/imxwd.c
index dd11a6261..1952548fa 100644
--- a/drivers/watchdog/imxwd.c
+++ b/drivers/watchdog/imxwd.c
@@ -97,9 +97,12 @@ static int imx21_watchdog_set_timeout(struct imx_wd *priv, int timeout)
 
 	dev_dbg(priv->dev, "%s: %d\n", __func__, timeout);
 
-	if (!timeout || timeout > 128)
+	if (timeout < -1 || timeout > 128)
 		return -EINVAL;
 
+	if (timeout == 0) /* bit 2 (WDE) cannot be set to 0 again */
+		return -ENOSYS;
+
 	if (timeout > 0)
 		val = ((timeout * 2 - 1) << 8) | IMX21_WDOG_WCR_SRS |
 			IMX21_WDOG_WCR_WDA;