diff --git a/homeassistant/components/wemo/light.py b/homeassistant/components/wemo/light.py
index 0767c6b6603..8a098904bb0 100644
--- a/homeassistant/components/wemo/light.py
+++ b/homeassistant/components/wemo/light.py
@@ -229,14 +229,13 @@ class WemoDimmer(WemoSubscriptionEntity, LightEntity):
         if ATTR_BRIGHTNESS in kwargs:
             brightness = kwargs[ATTR_BRIGHTNESS]
             brightness = int((brightness / 255) * 100)
-        else:
-            brightness = 255
-
-        with self._wemo_exception_handler("turn on"):
-            if self.wemo.on():
+            with self._wemo_exception_handler("set brightness"):
+                self.wemo.set_brightness(brightness)
+                self._state = WEMO_ON
+        else:
+            with self._wemo_exception_handler("turn on"):
+                self.wemo.on()
                 self._state = WEMO_ON
-
-            self.wemo.set_brightness(brightness)
 
         self.schedule_update_ha_state()