diff --git a/li.strolch.utils/src/main/java/li/strolch/utils/collections/MapOfLists.java b/li.strolch.utils/src/main/java/li/strolch/utils/collections/MapOfLists.java
index 543a15dec..a56dab935 100644
--- a/li.strolch.utils/src/main/java/li/strolch/utils/collections/MapOfLists.java
+++ b/li.strolch.utils/src/main/java/li/strolch/utils/collections/MapOfLists.java
@@ -117,7 +117,7 @@ public class MapOfLists<T, U> {
 
 	public int size(T t) {
 		List<U> list = this.mapOfLists.get(t);
-		if (list.size() == 0)
+		if (list == null || list.size() == 0)
 			return 0;
 		return list.size();
 	}
diff --git a/li.strolch.utils/src/main/java/li/strolch/utils/collections/MapOfSets.java b/li.strolch.utils/src/main/java/li/strolch/utils/collections/MapOfSets.java
index fef9328f9..ccb1f7ee4 100644
--- a/li.strolch.utils/src/main/java/li/strolch/utils/collections/MapOfSets.java
+++ b/li.strolch.utils/src/main/java/li/strolch/utils/collections/MapOfSets.java
@@ -135,7 +135,7 @@ public class MapOfSets<T, U> {
 
 	public int size(T t) {
 		Set<U> set = this.mapOfSets.get(t);
-		if (set.size() == 0)
+		if (set == null || set.size() == 0)
 			return 0;
 		return set.size();
 	}