diff --git a/CHANGELOG.md b/CHANGELOG.md
index 02ddbc647..47bd2e256 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@
 - [#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!
+- [#786](https://github.com/influxdata/telegraf/pull/786): Fix mqtt output username not being set. Thanks @msangoi!
 
 ## v0.10.4.1
 
diff --git a/plugins/outputs/mqtt/mqtt.go b/plugins/outputs/mqtt/mqtt.go
index 6f8abe954..10c1b1a9e 100644
--- a/plugins/outputs/mqtt/mqtt.go
+++ b/plugins/outputs/mqtt/mqtt.go
@@ -172,7 +172,7 @@ func (m *MQTT) createOpts() (*paho.ClientOptions, error) {
 	}
 
 	user := m.Username
-	if user == "" {
+	if user != "" {
 		opts.SetUsername(user)
 	}
 	password := m.Password