diff --git a/src/main/java/org/ntlab/citrusserver/repositories/BookManager.java b/src/main/java/org/ntlab/citrusserver/repositories/BookManager.java
index a8ca3df..5b0012e 100644
--- a/src/main/java/org/ntlab/citrusserver/repositories/BookManager.java
+++ b/src/main/java/org/ntlab/citrusserver/repositories/BookManager.java
@@ -123,6 +123,7 @@
 
     @Override
     public void accountDeleted(Account account) {
+        if(!booksMap.containsKey(account.getId())) return;
         for(Book book : booksMap.get(account.getId()).values()){
             notifyDeletedListener(account, book);