diff --git a/internal/models/running_output.go b/internal/models/running_output.go
index c926917d6..014202454 100644
--- a/internal/models/running_output.go
+++ b/internal/models/running_output.go
@@ -94,6 +94,9 @@ func NewRunningOutput(
 // AddMetric adds a metric to the output. This function can also write cached
 // points if FlushBufferWhenFull is true.
 func (ro *RunningOutput) AddMetric(m telegraf.Metric) {
+	ro.Lock()
+	defer ro.Unlock()
+
 	if m == nil {
 		return
 	}
@@ -115,8 +118,6 @@ func (ro *RunningOutput) AddMetric(m telegraf.Metric) {
 	}
 
 	if output, ok := ro.Output.(telegraf.AggregatingOutput); ok {
-		ro.Lock()
-		defer ro.Unlock()
 		output.Add(m)
 		return
 	}
@@ -134,6 +135,9 @@ func (ro *RunningOutput) AddMetric(m telegraf.Metric) {
 
 // Write writes all cached points to this output.
 func (ro *RunningOutput) Write() error {
+	ro.Lock()
+	defer ro.Unlock()
+
 	if output, ok := ro.Output.(telegraf.AggregatingOutput); ok {
 		metrics := output.Push()
 		ro.metrics.Add(metrics...)
@@ -188,8 +192,6 @@ func (ro *RunningOutput) write(metrics []telegraf.Metric) error {
 	if nMetrics == 0 {
 		return nil
 	}
-	ro.Lock()
-	defer ro.Unlock()
 	start := time.Now()
 	err := ro.Output.Write(metrics)
 	elapsed := time.Since(start)