diff --git a/base/src/main/java/de/staropensource/sosengine/base/types/ImmutableMap.java b/base/src/main/java/de/staropensource/sosengine/base/types/ImmutableMap.java
index 6478910..8e666b1 100644
--- a/base/src/main/java/de/staropensource/sosengine/base/types/ImmutableMap.java
+++ b/base/src/main/java/de/staropensource/sosengine/base/types/ImmutableMap.java
@@ -49,7 +49,7 @@ public class ImmutableMap<K, V> extends HashMap<K, V> {
      */
     public ImmutableMap(@NotNull Map<K, V> map) {
         for (K key : map.keySet())
-            put(key, map.get(key));
+            super.put(key, map.get(key));
     }
 
     /**