diff --git a/core/src/main/java/org/infinispan/persistence/manager/PersistenceManagerImpl.java b/core/src/main/java/org/infinispan/persistence/manager/PersistenceManagerImpl.java
index <HASH>..<HASH> 100644
--- a/core/src/main/java/org/infinispan/persistence/manager/PersistenceManagerImpl.java
+++ b/core/src/main/java/org/infinispan/persistence/manager/PersistenceManagerImpl.java
@@ -381,7 +381,7 @@ public class PersistenceManagerImpl implements PersistenceManager {
       return Flowable.fromPublisher(preloadCl.entryPublisher(null, true, true))
             .take(maxEntries)
             .observeOn(nonBlockingScheduler)
-            .flatMapSingle(me -> preloadKey(flaggedCache, me))
+            .concatMapSingle(me -> preloadKey(flaggedCache, me))
             .count()
             .subscribeOn(blockingScheduler)
             .to(RxJavaInterop.singleToCompletionStage())
changed to concat map to prevent concurrency