diff --git a/services/observatorium-metrics-template-overwrites.libsonnet b/services/observatorium-metrics-template-overwrites.libsonnet
index ee4c87d636..81096fbd49 100644
--- a/services/observatorium-metrics-template-overwrites.libsonnet
+++ b/services/observatorium-metrics-template-overwrites.libsonnet
@@ -171,6 +171,7 @@ local thanosRuleSyncer = import './sidecars/thanos-rule-syncer.libsonnet';
                         '--store.grpc.touched-series-limit=${THANOS_STORE_SERIES_TOUCHED_LIMIT}',
                         '--store.grpc.series-sample-limit=${THANOS_STORE_SERIES_SAMPLE_LIMIT}',
                         '--max-time=${THANOS_STORE_MAX_TIME}',
+                        '--store.enable-index-header-lazy-reader=${THANOS_STORE_ENABLE_INDEX_HEADER_LAZY_READER}',
                       ],
                     } else c
                     for c in super.containers
diff --git a/services/observatorium-metrics-template.jsonnet b/services/observatorium-metrics-template.jsonnet
index 8ceaa83a83..82908d1f0d 100644
--- a/services/observatorium-metrics-template.jsonnet
+++ b/services/observatorium-metrics-template.jsonnet
@@ -166,6 +166,7 @@ local obs = import 'observatorium.libsonnet';
     { name: 'THANOS_STORE_MEMORY_REQUEST', value: '1Gi' },
     { name: 'THANOS_STORE_REPLICAS', value: '5' },
     { name: 'THANOS_STORE_MAX_TIME', value: '9999-12-31T23:59:59Z' },
+    { name: 'THANOS_STORE_ENABLE_INDEX_HEADER_LAZY_READER', value: 'false' },
     { name: 'CONFIGMAP_RELOADER_IMAGE', value: 'quay.io/openshift/origin-configmap-reloader' },
     { name: 'CONFIGMAP_RELOADER_IMAGE_TAG', value: '4.5.0' },
   ],