diff --git a/src/fr/devinsy/sikevadb/Element.java b/src/fr/devinsy/sikevadb/Element.java
index 9180f0e..21f5adf 100644
--- a/src/fr/devinsy/sikevadb/Element.java
+++ b/src/fr/devinsy/sikevadb/Element.java
@@ -95,11 +95,15 @@ public class Element {
 	}
 
 	public void setArchiveDate(final Date archiveDate) {
-		this.archiveDate = archiveDate;
+		if (archiveDate == null) {
+			this.archiveDate = null;
+		} else {
+			this.archiveDate = (Date) archiveDate.clone();
+		}
 	}
 
 	public void setCreationDate(final Date creationDate) {
-		this.creationDate = creationDate;
+		this.creationDate = (Date) creationDate.clone();
 	}
 
 	public void setDigest(final String digest) {
@@ -107,7 +111,7 @@ public class Element {
 	}
 
 	public void setEditionDate(final Date editionDate) {
-		this.editionDate = editionDate;
+		this.editionDate = (Date) editionDate.clone();
 	}
 
 	public void setKey(final String key) {