diff --git a/src/main/java/net/berack/upo/ai/problem1/Puzzle8.java b/src/main/java/net/berack/upo/ai/problem1/Puzzle8.java
index 6a82935..6c7eae4 100644
--- a/src/main/java/net/berack/upo/ai/problem1/Puzzle8.java
+++ b/src/main/java/net/berack/upo/ai/problem1/Puzzle8.java
@@ -26,8 +26,9 @@ public class Puzzle8 implements Iterable<Integer> {
         for(var i = 0; i < n; i++) index[p1.puzzle[i]] = i;
         for(var i = 0; i < n; i++) {
             var curr = p2.puzzle[i];
-            var i2 = index[curr];
+            if(curr == 0) continue;
 
+            var i2 = index[curr];
             sum += Math.abs((i / LENGTH) - (i2 / LENGTH)) + Math.abs((i % LENGTH) - (i2 % LENGTH));
         }
         return sum;
@@ -265,7 +266,7 @@ public class Puzzle8 implements Iterable<Integer> {
     public List<Move> solve(Puzzle8 goal) {
         if(!this.isSolvable(goal)) return null;
 
-        var aStar = new AStar<Puzzle8, Move>(Puzzle8::availableMoves, (p, m) -> new Puzzle8(p, m));
+        var aStar = new AStar<Puzzle8, Move>(Puzzle8::availableMoves, Puzzle8::new);
         aStar.setHeuristic(HEURISTIC_MANHATTAN);
 
         return aStar.solve(this, Objects.requireNonNull(goal));
diff --git a/src/test/java/net/berack/upo/ai/problem1/TestPuzzle.java b/src/test/java/net/berack/upo/ai/problem1/TestPuzzle.java
index 040f800..2343bb7 100644
--- a/src/test/java/net/berack/upo/ai/problem1/TestPuzzle.java
+++ b/src/test/java/net/berack/upo/ai/problem1/TestPuzzle.java
@@ -126,11 +126,8 @@ public class TestPuzzle {
     public void testSolve() {
         var puzzle = new Puzzle8(3,5,6,1,2,4,0,7,8);
         var puzzleGoal = new Puzzle8(1,2,3,4,5,6,7,8,0);
-        var solution = new Puzzle8.Move[] {RIGHT, UP, RIGHT, UP, LEFT, LEFT, DOWN, RIGHT, DOWN, RIGHT, UP, UP, LEFT, DOWN, RIGHT, DOWN};
         var actual = puzzle.solve(puzzleGoal).toArray(new Puzzle8.Move[0]);
 
-        assertArrayEquals(solution, actual);
-
         for(var move : actual) puzzle.move(move);
         assertEquals(puzzleGoal, puzzle);
     }