diff --git a/library/src/main/java/org/mustangproject/DirectDebit.java b/library/src/main/java/org/mustangproject/DirectDebit.java
index e4ac9a85..d90ba661 100644
--- a/library/src/main/java/org/mustangproject/DirectDebit.java
+++ b/library/src/main/java/org/mustangproject/DirectDebit.java
@@ -9,12 +9,12 @@ public class DirectDebit implements IZUGFeRDTradeSettlementDebit {
 	/**
 	 * Debited account identifier (BT-91)
 	 */
-	protected final String IBAN;
+	protected String IBAN;
 
 	/**
 	 * Mandate reference identifier (BT-89)
 	 */
-	protected final String mandate;
+	protected String mandate;
 
 	/**
 	 * bean constructor