diff --git a/src/fr/devinsy/sikevadb/core/XMLSikevaDB.java b/src/fr/devinsy/sikevadb/core/XMLSikevaDB.java
index 428564a..945b2b3 100644
--- a/src/fr/devinsy/sikevadb/core/XMLSikevaDB.java
+++ b/src/fr/devinsy/sikevadb/core/XMLSikevaDB.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2013-2017 Christian Pierre MOMON <christian.momon@devinsy.fr>
+ * Copyright (C) 2013-2018 Christian Pierre MOMON <christian.momon@devinsy.fr>
  * 
  * This file is part of SikevaDB, simple key value database.
  * 
@@ -75,11 +75,11 @@ public class XMLSikevaDB
 	{
 		if (out == null)
 		{
-			throw new NullPointerException("out is null.");
+			throw new IllegalArgumentException("out is null.");
 		}
 		else if (source == null)
 		{
-			throw new NullPointerException("source is null.");
+			throw new IllegalArgumentException("source is null.");
 		}
 		else if (fileName == null)
 		{
@@ -224,11 +224,11 @@ public class XMLSikevaDB
 
 		if (out == null)
 		{
-			throw new NullPointerException("out is null.");
+			throw new IllegalArgumentException("out is null.");
 		}
 		else if (source == null)
 		{
-			throw new NullPointerException("element is null.");
+			throw new IllegalArgumentException("element is null.");
 		}
 		else
 		{
@@ -277,7 +277,7 @@ public class XMLSikevaDB
 	{
 		if (out == null)
 		{
-			throw new NullPointerException("out is null.");
+			throw new IllegalArgumentException("out is null.");
 		}
 		else if (source == null)
 		{