diff --git a/src/main/java/org/codelibs/fess/job/PurgeThumbnailJob.java b/src/main/java/org/codelibs/fess/job/PurgeThumbnailJob.java
index 1cd302c6c..4259815b2 100644
--- a/src/main/java/org/codelibs/fess/job/PurgeThumbnailJob.java
+++ b/src/main/java/org/codelibs/fess/job/PurgeThumbnailJob.java
@@ -22,7 +22,7 @@ import org.slf4j.LoggerFactory;
 public class PurgeThumbnailJob {
     private static final Logger logger = LoggerFactory.getLogger(PurgeThumbnailJob.class);
 
-    private long expiry;
+    private long expiry = 30 * 24 * 60 * 60 * 1000L;
 
     public String execute() {
         try {
@@ -39,7 +39,9 @@ public class PurgeThumbnailJob {
     }
 
     public PurgeThumbnailJob expiry(final long expiry) {
-        this.expiry = expiry;
+        if (expiry > 0) {
+            this.expiry = expiry;
+        }
         return this;
     }
 }
diff --git a/src/main/resources/fess_indices/.fess_config/scheduled_job.bulk b/src/main/resources/fess_indices/.fess_config/scheduled_job.bulk
index 3d51200b4..d1b0fe320 100644
--- a/src/main/resources/fess_indices/.fess_config/scheduled_job.bulk
+++ b/src/main/resources/fess_indices/.fess_config/scheduled_job.bulk
@@ -11,6 +11,6 @@
 {"index":{"_index":".fess_config","_type":"scheduled_job","_id":"thumbnail_generate"}}
 {"name":"Thumbnail Generator","target":"all","cronExpression":"* * * * *","scriptType":"groovy","scriptData":"return container.getComponent(\"generateThumbnailJob\").execute();","jobLogging":false,"crawler":false,"available":true,"sortOrder":6,"createdBy":"system","createdTime":0,"updatedBy":"system","updatedTime":0}
 {"index":{"_index":".fess_config","_type":"scheduled_job","_id":"thumbnail_purger"}}
-{"name":"Thumbnail Purger","target":"all","cronExpression":"0 0 * * *","scriptType":"groovy","scriptData":"return container.getComponent(\"purgeThumbnailJob\").expiry(30 * 24 * 60 * 60 * 1000).execute();","jobLogging":true,"crawler":false,"available":true,"sortOrder":7,"createdBy":"system","createdTime":0,"updatedBy":"system","updatedTime":0}
+{"name":"Thumbnail Purger","target":"all","cronExpression":"0 0 * * *","scriptType":"groovy","scriptData":"return container.getComponent(\"purgeThumbnailJob\").expiry(30 * 24 * 60 * 60 * 1000L).execute();","jobLogging":true,"crawler":false,"available":true,"sortOrder":7,"createdBy":"system","createdTime":0,"updatedBy":"system","updatedTime":0}
 {"index":{"_index":".fess_config","_type":"scheduled_job","_id":"ping_es"}}
 {"name":"Ping Elasticsearch","target":"all","cronExpression":"* * * * *","scriptType":"groovy","scriptData":"return container.getComponent(\"pingEsJob\").execute();","jobLogging":false,"crawler":false,"available":true,"sortOrder":8,"createdBy":"system","createdTime":0,"updatedBy":"system","updatedTime":0}