diff --git a/exporter.go b/exporter.go
index f8eaedd..e22f5e4 100644
--- a/exporter.go
+++ b/exporter.go
@@ -458,7 +458,6 @@ func (b *Exporter) handleEvent(event Event) {
 
 	metricName := ""
 	prometheusLabels := event.Labels()
-	sortedLabelNames := getSortedLabelNames(prometheusLabels)
 	if present {
 		if mapping.Name == "" {
 			log.Debugf("The mapping of '%s' for match '%s' generates an empty metric name", event.MetricName(), mapping.Match)
@@ -475,6 +474,7 @@ func (b *Exporter) handleEvent(event Event) {
 		metricName = escapeMetricName(event.MetricName())
 	}
 
+	sortedLabelNames := getSortedLabelNames(prometheusLabels)
 	switch ev := event.(type) {
 	case *CounterEvent:
 		// We don't accept negative values for counters. Incrementing the counter with a negative number