diff --git a/core/src/test/java/org/elasticsearch/test/ESIntegTestCase.java b/core/src/test/java/org/elasticsearch/test/ESIntegTestCase.java
index 14b65265e5d..0597ad9078a 100644
--- a/core/src/test/java/org/elasticsearch/test/ESIntegTestCase.java
+++ b/core/src/test/java/org/elasticsearch/test/ESIntegTestCase.java
@@ -1479,18 +1479,18 @@ public abstract class ESIntegTestCase extends ESTestCase {
         if (rarely()) {
             if (rarely()) {
                 client().admin().indices().prepareRefresh(indices).setIndicesOptions(IndicesOptions.lenientExpandOpen()).execute(
-                        new LatchedActionListener<RefreshResponse>(newLatch(inFlightAsyncOperations)));
+                        new LatchedActionListener<>(newLatch(inFlightAsyncOperations)));
             } else if (maybeFlush && rarely()) {
                 if (randomBoolean()) {
                     client().admin().indices().prepareFlush(indices).setIndicesOptions(IndicesOptions.lenientExpandOpen()).execute(
-                            new LatchedActionListener<FlushResponse>(newLatch(inFlightAsyncOperations)));
-                } else {
+                            new LatchedActionListener<>(newLatch(inFlightAsyncOperations)));
+                } else if (isInternalCluster()) {
                     internalCluster().getInstance(SyncedFlushService.class).attemptSyncedFlush(indices, IndicesOptions.lenientExpandOpen(),
-                            new LatchedActionListener<IndicesSyncedFlushResult>(newLatch(inFlightAsyncOperations)));
+                            new LatchedActionListener<>(newLatch(inFlightAsyncOperations)));
                 }
             } else if (rarely()) {
                 client().admin().indices().prepareOptimize(indices).setIndicesOptions(IndicesOptions.lenientExpandOpen()).setMaxNumSegments(between(1, 10)).setFlush(maybeFlush && randomBoolean()).execute(
-                        new LatchedActionListener<OptimizeResponse>(newLatch(inFlightAsyncOperations)));
+                        new LatchedActionListener<>(newLatch(inFlightAsyncOperations)));
             }
         }
         while (inFlightAsyncOperations.size() > MAX_IN_FLIGHT_ASYNC_INDEXES) {