diff --git a/src/main/java/org/compuscene/metrics/prometheus/PrometheusMetricsCollector.java b/src/main/java/org/compuscene/metrics/prometheus/PrometheusMetricsCollector.java
index 4e0394c2..4f3c4a0e 100644
--- a/src/main/java/org/compuscene/metrics/prometheus/PrometheusMetricsCollector.java
+++ b/src/main/java/org/compuscene/metrics/prometheus/PrometheusMetricsCollector.java
@@ -109,7 +109,7 @@ private void updateClusterMetrics(ClusterHealthResponse chr) {
 
             catalog.setClusterGauge("cluster_shards_number", chr.getActiveShards(), "active");
             catalog.setClusterGauge("cluster_shards_number", chr.getActivePrimaryShards(), "active_primary");
-            catalog.setClusterGauge("cluster_shards_number", chr.getDelayedUnassignedShards(), "unassigned");
+            catalog.setClusterGauge("cluster_shards_number", chr.getDelayedUnassignedShards(), "delayed_unassigned");
             catalog.setClusterGauge("cluster_shards_number", chr.getInitializingShards(), "initializing");
             catalog.setClusterGauge("cluster_shards_number", chr.getRelocatingShards(), "relocating");
             catalog.setClusterGauge("cluster_shards_number", chr.getUnassignedShards(), "unassigned");