diff --git a/li.strolch.model/src/main/java/li/strolch/model/activity/Activity.java b/li.strolch.model/src/main/java/li/strolch/model/activity/Activity.java
index 54d960dc9..600b02852 100644
--- a/li.strolch.model/src/main/java/li/strolch/model/activity/Activity.java
+++ b/li.strolch.model/src/main/java/li/strolch/model/activity/Activity.java
@@ -179,7 +179,10 @@ public class Activity extends GroupedParameterizedElement
 	 * @return the removed element, or null if it does not exist
 	 */
 	public IActivityElement remove(String id) {
-		return this.elements.remove(id);
+		IActivityElement element = this.elements.remove(id);
+		if (element != null)
+			element.setParent(null);
+		return element;
 	}
 
 	/**