diff --git a/server/src/main/java/org/opensearch/action/admin/cluster/health/ClusterHealthResponse.java b/server/src/main/java/org/opensearch/action/admin/cluster/health/ClusterHealthResponse.java
index 78dcd559628a5..d20c201c4f97b 100644
--- a/server/src/main/java/org/opensearch/action/admin/cluster/health/ClusterHealthResponse.java
+++ b/server/src/main/java/org/opensearch/action/admin/cluster/health/ClusterHealthResponse.java
@@ -240,7 +240,7 @@ public ClusterHealthResponse(
 
     public ClusterHealthResponse(
         String clusterName,
-        String[] concreteIndices,
+        Set<String> concreteIndices,
         ClusterHealthRequest clusterHealthRequest,
         ClusterState clusterState,
         int numberOfPendingTasks,
@@ -287,7 +287,7 @@ public ClusterHealthResponse(
         ClusterHealthRequest clusterHealthRequest,
         ClusterState clusterState,
         ClusterSettings clusterSettings,
-        String[] concreteIndices,
+        Set<String> concreteIndices,
         String awarenessAttributeName,
         int numberOfPendingTasks,
         int numberOfInFlightFetch,
diff --git a/server/src/main/java/org/opensearch/cluster/health/ClusterStateHealth.java b/server/src/main/java/org/opensearch/cluster/health/ClusterStateHealth.java
index c8e087e354232..c559cc7b6e9b2 100644
--- a/server/src/main/java/org/opensearch/cluster/health/ClusterStateHealth.java
+++ b/server/src/main/java/org/opensearch/cluster/health/ClusterStateHealth.java
@@ -153,7 +153,7 @@ public ClusterStateHealth(final ClusterState clusterState, final Set<String> con
 
     public ClusterStateHealth(
         final ClusterState clusterState,
-        final String[] concreteIndices,
+        final Set<String> concreteIndices,
         final ClusterHealthRequest.Level healthLevel
     ) {
         numberOfNodes = clusterState.nodes().getSize();