diff --git a/core/src/test/java/ai/timefold/solver/core/impl/domain/solution/cloner/AbstractSolutionClonerTest.java b/core/src/test/java/ai/timefold/solver/core/impl/domain/solution/cloner/AbstractSolutionClonerTest.java
index 2082729f5e..4ab4522423 100644
--- a/core/src/test/java/ai/timefold/solver/core/impl/domain/solution/cloner/AbstractSolutionClonerTest.java
+++ b/core/src/test/java/ai/timefold/solver/core/impl/domain/solution/cloner/AbstractSolutionClonerTest.java
@@ -902,6 +902,8 @@ private void assertTestdataVariousTypes(TestdataVariousTypes original, TestdataV
             softly.assertThat(cloned.deepClonedListRef)
                     .first()
                     .isSameAs(original.deepClonedListRef.get(0));
+            softly.assertThat(cloned.extraDeepClonedObject).isNotSameAs(original.extraDeepClonedObject);
+            softly.assertThat(cloned.extraDeepClonedObject.id).isSameAs(original.extraDeepClonedObject.id);
         });
         assertSoftly(softly -> {
             softly.assertThat(cloned.shallowClonedListRef).isSameAs(original.shallowClonedListRef);