diff --git a/CHANGELOG.md b/CHANGELOG.md
index d2181787a0282..02ddbc647039d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@
 - [#748](https://github.com/influxdata/telegraf/issues/748): Fix sensor plugin split on ":"
 - [#722](https://github.com/influxdata/telegraf/pull/722): Librato output plugin fixes. Thanks @chrusty!
 - [#745](https://github.com/influxdata/telegraf/issues/745): Fix Telegraf toml parse panic on large config files. Thanks @titilambert!
+- [#781](https://github.com/influxdata/telegraf/pull/781): Fix mqtt_consumer username not being set. Thanks @chaton78!
 
 ## v0.10.4.1
 
diff --git a/plugins/inputs/mqtt_consumer/mqtt_consumer.go b/plugins/inputs/mqtt_consumer/mqtt_consumer.go
index 2d0fbef06f882..42cadfd60e740 100644
--- a/plugins/inputs/mqtt_consumer/mqtt_consumer.go
+++ b/plugins/inputs/mqtt_consumer/mqtt_consumer.go
@@ -181,7 +181,7 @@ func (m *MQTTConsumer) createOpts() (*mqtt.ClientOptions, error) {
 	}
 
 	user := m.Username
-	if user == "" {
+	if user != "" {
 		opts.SetUsername(user)
 	}
 	password := m.Password