diff --git a/documents/src/main/java/de/srsoftware/umbrella/documents/model/Document.java b/documents/src/main/java/de/srsoftware/umbrella/documents/model/Document.java
index 669eba1..b88b8c4 100644
--- a/documents/src/main/java/de/srsoftware/umbrella/documents/model/Document.java
+++ b/documents/src/main/java/de/srsoftware/umbrella/documents/model/Document.java
@@ -217,7 +217,7 @@ public final class Document implements Mappable {
 		map.put(FIELD_TYPE, type.name());
 		map.put(DATE, date);
 		map.put(STATE, state.code);
-		map.put(FIELD_DELIVERY, delivery);
+		map.put(FIELD_DELIVERY, delivery == null ? "" : delivery);
 		map.put(FIELD_HEAD, Map.of(SOURCE,head,RENDERED,markdown(head)));
 		map.put(FIELD_FOOTER, Map.of(SOURCE,footer,RENDERED,markdown(footer)));
 		map.put(FIELD_CURRENCY, currency);