diff --git a/src/main/java/org/wikitolearn/midtier/course/service/PageService.java b/src/main/java/org/wikitolearn/midtier/course/service/PageService.java
index ee74b00..b8f8383 100644
--- a/src/main/java/org/wikitolearn/midtier/course/service/PageService.java
+++ b/src/main/java/org/wikitolearn/midtier/course/service/PageService.java
@@ -1,75 +1,81 @@
 package org.wikitolearn.midtier.course.service;
 
+import java.util.Collections;
 import java.util.List;
+import java.util.Optional;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.event.EventListener;
 import org.springframework.stereotype.Service;
 import org.springframework.util.MultiValueMap;
 import org.wikitolearn.midtier.course.client.PageClient;
 import org.wikitolearn.midtier.course.entity.Chapter;
 import org.wikitolearn.midtier.course.entity.EntityList;
 import org.wikitolearn.midtier.course.entity.Page;
 import org.wikitolearn.midtier.course.event.ChapterDeleted;
 import org.wikitolearn.midtier.course.event.PageDeleted;
 import org.wikitolearn.midtier.course.event.PageUpdated;
 
 import com.fasterxml.jackson.core.JsonProcessingException;
 
 import lombok.extern.slf4j.Slf4j;
 
 @Service
 @Slf4j
 public class PageService {
   @Autowired
   private ApplicationEventPublisher applicationEventPublisher;
 
   @Autowired
   private PageClient pageClient;
 
   public EntityList<Page> findAll() {
     return pageClient.findAll();
   }
 
   public Page find(String pageId, MultiValueMap<String, String> params) {
     return pageClient.find(pageId, params);
   }
 
   public List<Page> save(List<Page> pages) {
     pages.stream().forEach(p -> {
       Page saved;
       try {
         saved = this.save(p);
         p.setId(saved.getId());
         p.setVersion(saved.getVersion());
       } catch (JsonProcessingException e) {
         log.error(e.getMessage());
       }
     });
     return pages;
   }
 
   public Page save(Page page) throws JsonProcessingException {
     return pageClient.store(page);
   }
 
   public Page update(Page page) throws JsonProcessingException {
     Page updatedPage = pageClient.update(page);
     applicationEventPublisher.publishEvent(new PageUpdated(this, updatedPage));
     return updatedPage;
   }
-  
+
   public void delete(Page page, boolean isBulkDelete) {
     // FIXME: workaround, see T9150
     page = pageClient.find(page.getId(), null);
     pageClient.delete(page);
     applicationEventPublisher.publishEvent(new PageDeleted(this, page, isBulkDelete));
   }
-  
+
   @EventListener
   public void handleChapterDeletedEvent(ChapterDeleted event) throws JsonProcessingException {
     Chapter deletedChapter = event.getChapter();
-    deletedChapter.getPages().parallelStream().forEach(p -> this.delete(p, true));
+    Optional
+      .ofNullable(deletedChapter.getPages())
+      .orElseGet(Collections::emptyList)
+      .parallelStream()
+      .forEach(p -> this.delete(p, true));
   }
 }