diff --git a/server/build.gradle b/server/build.gradle
index 0f9798c53f22d..9a87155eb86c1 100644
--- a/server/build.gradle
+++ b/server/build.gradle
@@ -132,6 +132,9 @@ if (BuildParams.isSnapshotBuild() == false) {
     tasks.named("test").configure {
         systemProperty 'es.index_mode_feature_flag_registered', 'true'
     }
+    tasks.named("internalClusterTest").configure {
+        systemProperty 'es.index_mode_feature_flag_registered', 'true'
+    }
 }
 
 tasks.named("thirdPartyAudit").configure {
diff --git a/server/src/main/java/org/elasticsearch/index/IndexSettings.java b/server/src/main/java/org/elasticsearch/index/IndexSettings.java
index 23df096597588..643b43b9c9361 100644
--- a/server/src/main/java/org/elasticsearch/index/IndexSettings.java
+++ b/server/src/main/java/org/elasticsearch/index/IndexSettings.java
@@ -813,7 +813,9 @@ public IndexSettings(final IndexMetadata indexMetadata, final Settings nodeSetti
         scopedSettings.addSettingsUpdateConsumer(INDEX_MAPPING_DEPTH_LIMIT_SETTING, this::setMappingDepthLimit);
         scopedSettings.addSettingsUpdateConsumer(INDEX_MAPPING_FIELD_NAME_LENGTH_LIMIT_SETTING, this::setMappingFieldNameLengthLimit);
         scopedSettings.addSettingsUpdateConsumer(INDEX_MAPPING_DIMENSION_FIELDS_LIMIT_SETTING, this::setMappingDimensionFieldsLimit);
-        scopedSettings.addSettingsUpdateConsumer(TIME_SERIES_END_TIME, this::updateTimeSeriesEndTime);
+        if (IndexSettings.isTimeSeriesModeEnabled()) {
+            scopedSettings.addSettingsUpdateConsumer(TIME_SERIES_END_TIME, this::updateTimeSeriesEndTime);
+        }
     }
 
     private void setSearchIdleAfter(TimeValue searchIdleAfter) {