diff --git a/homeassistant/components/mqtt/discovery.py b/homeassistant/components/mqtt/discovery.py
index 6a0b8555ddb..fdb7948e4bf 100644
--- a/homeassistant/components/mqtt/discovery.py
+++ b/homeassistant/components/mqtt/discovery.py
@@ -120,9 +120,9 @@ async def async_start(hass: HomeAssistantType, discovery_topic, hass_config,
 
             config_entries_key = '{}.{}'.format(component, platform)
             if config_entries_key not in hass.data[CONFIG_ENTRY_IS_SETUP]:
+                hass.data[CONFIG_ENTRY_IS_SETUP].add(config_entries_key)
                 await hass.config_entries.async_forward_entry_setup(
                     config_entry, component)
-                hass.data[CONFIG_ENTRY_IS_SETUP].add(config_entries_key)
 
             async_dispatcher_send(hass, MQTT_DISCOVERY_NEW.format(
                 component, platform), payload)