diff --git a/homeassistant/components/lcn/services.py b/homeassistant/components/lcn/services.py
index c55e6586edf..e46328069e1 100644
--- a/homeassistant/components/lcn/services.py
+++ b/homeassistant/components/lcn/services.py
@@ -288,7 +288,7 @@ class SendKeys(LcnServiceCall):
                 vol.Upper, vol.In(SENDKEYCOMMANDS)
             ),
             vol.Optional(CONF_TIME, default=0): cv.positive_int,
-            vol.Optional(CONF_TIME_UNIT, default=TIME_SECONDS): vol.All(
+            vol.Optional(CONF_TIME_UNIT, default="S"): vol.All(
                 vol.Upper, vol.In(TIME_UNITS)
             ),
         }