diff --git a/core/src/main/java/de/srsoftware/umbrella/core/model/Task.java b/core/src/main/java/de/srsoftware/umbrella/core/model/Task.java
index 7fa25ee8..6170cf97 100644
--- a/core/src/main/java/de/srsoftware/umbrella/core/model/Task.java
+++ b/core/src/main/java/de/srsoftware/umbrella/core/model/Task.java
@@ -220,7 +220,7 @@ public class Task implements Mappable {
 
 	public Task tags(Collection<String> newValue){
 		tags.clear();
-		tags.addAll(newValue);
+		if (newValue != null) tags.addAll(newValue);
 		return this;
 	}