diff --git a/kafka_exporter.go b/kafka_exporter.go
index 577fdfe5..636188e8 100644
--- a/kafka_exporter.go
+++ b/kafka_exporter.go
@@ -635,6 +635,7 @@ func (e *Exporter) collect(ch chan<- prometheus.Metric) {
 					ch <- prometheus.MustNewConstMetric(
 						consumergroupCurrentOffset, prometheus.GaugeValue, float64(currentOffset), group.GroupId, topic, strconv.FormatInt(int64(partition), 10),
 					)
+					e.mu.Lock()
 					currentPartitionOffset, currentPartitionOffsetError := e.client.GetOffset(topic, partition, sarama.OffsetNewest) 
 					if currentPartitionOffsetError != nil {
 						klog.Errorf("Cannot get current offset of topic %s partition %d: %v", topic, partition, currentPartitionOffsetError)
@@ -656,6 +657,7 @@ func (e *Exporter) collect(ch chan<- prometheus.Metric) {
 							consumergroupLag, prometheus.GaugeValue, float64(lag), group.GroupId, topic, strconv.FormatInt(int64(partition), 10),
 						)
 					} 
+					e.mu.Unlock()
 				}
 				ch <- prometheus.MustNewConstMetric(
 					consumergroupCurrentOffsetSum, prometheus.GaugeValue, float64(currentOffsetSum), group.GroupId, topic,