diff --git a/src/Aufgabe6Test.java b/src/Aufgabe6Test.java
index 311ca56..c05400a 100644
--- a/src/Aufgabe6Test.java
+++ b/src/Aufgabe6Test.java
@@ -113,4 +113,21 @@ public class Aufgabe6Test {
         }
         assertEquals(12, count);
     }
+
+    @Test
+    public void testIterator() {
+        NamedBody sun1, mercury1, venus1;
+        sun1 = new NamedBody(SolSystem4.SUN_NAMED);
+        mercury1 = new NamedBody(SolSystem4.MERCURY_NAMED);
+        venus1 = new NamedBody(SolSystem4.VENUS_NAMED);
+
+        MassiveForceTreeMap map = new MassiveForceTreeMap();
+
+        map.put(sun1, new Vector3());
+        map.put(mercury1, new Vector3());
+        map.put(venus1, new Vector3());
+        for (Massive m : map.getKeys().toList()) {
+            System.out.println(m);
+        }
+    }
 }
diff --git a/src/MassiveLinkedList.java b/src/MassiveLinkedList.java
index d2d65a9..ebe08c0 100644
--- a/src/MassiveLinkedList.java
+++ b/src/MassiveLinkedList.java
@@ -4,7 +4,7 @@ import java.util.Iterator;
  * A list of massive objects implemented as a linked list.
  * The number of elements of the list is not limited.
  */
-public class MassiveLinkedList implements Iterable<Massive> {
+public class MassiveLinkedList implements MassiveIterable {
     private int size = 0;
     private Item first;
     private Item last;
@@ -172,8 +172,8 @@ public class MassiveLinkedList implements Iterable<Massive> {
     }
 
     @Override
-    public Iterator<Massive> iterator() {
-        return new Iterator<>() {
+    public MassiveIterator iterator() {
+        return new MassiveIterator() {
             Item ptr = first;
             boolean yieldedFirst = false;