diff --git a/resources/bytecode/javFiles/PaternMatchingHaskellStyle.jav b/resources/bytecode/javFiles/PaternMatchingHaskellStyle.jav
index ba3e7771..a1283113 100644
--- a/resources/bytecode/javFiles/PaternMatchingHaskellStyle.jav
+++ b/resources/bytecode/javFiles/PaternMatchingHaskellStyle.jav
@@ -1,14 +1,26 @@
+import java.lang.Boolean;
+
 sealed interface List<T> permits LinkedElem, Elem {}
 
 public record LinkedElem<T>(T a, List<T> l) implements List<T> {}
 public record Elem<T>(T a) implements List<T> {}
 
 public class PaternMatchingHaskellStyle {
-   public append(LinkedElem(a, Elem(e)), l2) {
-   	  return new LinkedElem<>(a, new LinkedElem<>(e, l2));
-   }
 
-   public append(LinkedElem(a, r), l2) {
-   	  return new LinkedElem<>(a, append(r, l2));
-   }
-}
+    public append(LinkedElem(a, b), list2) {
+        if (b instanceof Elem<?>) {
+            return handleElem(a, (Elem<?>) b, list2);
+        } else if (b instanceof LinkedElem<?>) {
+            return handleLinkedElem(a, (LinkedElem<?>) b, list2);
+        }
+        return null;
+    }
+
+    private handleElem(a, Elem(e), list2) {
+        return new LinkedElem<>(a, new LinkedElem<>(e, list2));
+    }
+
+    private handleLinkedElem(a, LinkedElem(a,r), list2) {
+        return new LinkedElem<>(a, append(r, list2));
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/TestComplete.java b/src/test/java/TestComplete.java
index 1d314087..26e73bd8 100644
--- a/src/test/java/TestComplete.java
+++ b/src/test/java/TestComplete.java
@@ -869,11 +869,11 @@ public class TestComplete {
         var instance = clazz.getDeclaredConstructor().newInstance();
         var m = clazz.getDeclaredMethod("append", R, I);
 
-        //var x = rctor.newInstance(rctor.newInstance(0, rctor.newInstance(0, r2ctor.newInstance(0))), 0);
-        //var y = rctor.newInstance(r2ctor.newInstance(0), 0);
+        var x = rctor.newInstance(rctor.newInstance(0, rctor.newInstance(0, r2ctor.newInstance(0))), r2ctor.newInstance(0));
+        var y = rctor.newInstance(r2ctor.newInstance(0), r2ctor.newInstance(0));
 
-        //assertEquals(m.invoke(instance, x, y), 10);
-        //assertEquals(m.invoke(instance, y, y), 40.0);
+        assertEquals(m.invoke(instance, x, y), 10);
+        assertEquals(m.invoke(instance, y, y), 0);
 
     }