diff --git a/phase4-dbnalliance-client/src/main/java/com/helger/phase4/dbnalliance/Phase4DBNAllianceSender.java b/phase4-dbnalliance-client/src/main/java/com/helger/phase4/dbnalliance/Phase4DBNAllianceSender.java
index 61b8810e8..c09a80235 100644
--- a/phase4-dbnalliance-client/src/main/java/com/helger/phase4/dbnalliance/Phase4DBNAllianceSender.java
+++ b/phase4-dbnalliance-client/src/main/java/com/helger/phase4/dbnalliance/Phase4DBNAllianceSender.java
@@ -92,6 +92,8 @@ private static XHE10XHEType _createXHE (@Nonnull final IParticipantIdentifier aS
     aData.setCreationDateAndTime (MetaAS4Manager.getTimestampMgr ().getCurrentXMLDateTime ());
     
     final DBNAlliancePayload aPayload = new DBNAlliancePayload (IF);
+    // Content type code is mandatory
+    aPayload.setContentTypeCode ("application/xml");
     aPayload.setCustomizationID (null, aDocTypeID.getValue ());
     aPayload.setProfileID (aProcID.getScheme (), aProcID.getValue ());