diff --git a/pkg/controller/cluster/prometheus.go b/pkg/controller/cluster/prometheus.go
index 8f15f9e4967..1a80450bde5 100644
--- a/pkg/controller/cluster/prometheus.go
+++ b/pkg/controller/cluster/prometheus.go
@@ -92,7 +92,7 @@ func getPrometheusMetricsForTenantWithRetry(tenant *miniov2.Tenant, bearer strin
 				if err != nil {
 					klog.Infof("%s/%s Could not parse usage for tenant: %s", tenant.Namespace, tenant.Name, line)
 				}
-				promMetrics.Usage = int64(usage)
+				promMetrics.Usage = promMetrics.Usage + int64(usage)
 			}
 		}
 		// Usable capacity