diff --git a/src/test/java/net/kemitix/node/ImmutableNodeItemTest.java b/src/test/java/net/kemitix/node/ImmutableNodeItemTest.java
index 91eee8a..c4c4bc7 100644
--- a/src/test/java/net/kemitix/node/ImmutableNodeItemTest.java
+++ b/src/test/java/net/kemitix/node/ImmutableNodeItemTest.java
@@ -126,7 +126,7 @@ public class ImmutableNodeItemTest {
         immutableNode = Nodes.asImmutable(Nodes.unnamedRoot("subject"));
         expectImmutableException();
         //when
-        immutableNode.setParent(null);
+        immutableNode.setParent(Nodes.unnamedRoot("child"));
     }
 
     @Test