diff --git a/src/main/java/ca/joeltherrien/randomforest/tree/ForestTrainer.java b/src/main/java/ca/joeltherrien/randomforest/tree/ForestTrainer.java
index 2686666..5d721f1 100644
--- a/src/main/java/ca/joeltherrien/randomforest/tree/ForestTrainer.java
+++ b/src/main/java/ca/joeltherrien/randomforest/tree/ForestTrainer.java
@@ -17,11 +17,10 @@
 package ca.joeltherrien.randomforest.tree;
 
 import ca.joeltherrien.randomforest.Bootstrapper;
-import ca.joeltherrien.randomforest.utils.DataUtils;
 import ca.joeltherrien.randomforest.Row;
 import ca.joeltherrien.randomforest.Settings;
 import ca.joeltherrien.randomforest.covariates.Covariate;
-import ca.joeltherrien.randomforest.utils.Utils;
+import ca.joeltherrien.randomforest.utils.DataUtils;
 import lombok.AccessLevel;
 import lombok.AllArgsConstructor;
 import lombok.Builder;
@@ -31,6 +30,7 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Random;
+import java.util.UUID;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ThreadLocalRandom;
@@ -110,7 +110,7 @@ public class ForestTrainer<Y, TO, FO> {
                 System.out.print("\rFinished " + treeCount.get() + "/" + ntree + " trees");
             }
 
-            final Runnable worker = new TreeSavedWorker(data, "tree-" + Utils.formatNumber(j+1, ntree) + ".tree", treeCount);
+            final Runnable worker = new TreeSavedWorker(data, "tree-" + UUID.randomUUID() + ".tree", treeCount);
             worker.run();
 
         }
@@ -191,7 +191,7 @@ public class ForestTrainer<Y, TO, FO> {
         final AtomicInteger treeCount = new AtomicInteger(treeFiles.length); // tracks how many trees are finished
 
         for(int j=treeCount.get(); j<ntree; j++){
-            final Runnable worker = new TreeSavedWorker(data, "tree-" + Utils.formatNumber(j+1, ntree) + ".tree", treeCount);
+            final Runnable worker = new TreeSavedWorker(data, "tree-" + UUID.randomUUID() + ".tree", treeCount);
             executorService.execute(worker);
         }
 
diff --git a/src/main/java/ca/joeltherrien/randomforest/utils/Utils.java b/src/main/java/ca/joeltherrien/randomforest/utils/Utils.java
index 7939b86..70e3e1f 100644
--- a/src/main/java/ca/joeltherrien/randomforest/utils/Utils.java
+++ b/src/main/java/ca/joeltherrien/randomforest/utils/Utils.java
@@ -208,26 +208,4 @@ public final class Utils {
         return map;
     }
 
-    /**
-     * When saving trees we typically save them as tree-1.tree, tree-2.tree. This is fine until we get tree-10.tree, which
-     * when sorted alphabetically goes before tree-2.tree. We should instead save tree-01.tree, ... tree-10.tree.
-     *
-     * We need to set the number of 0s though based on ntree.
-     *
-     * @return
-     */
-    public static String formatNumber(int currentTreeNumber, int maxNumberOfTrees){
-        final int numDigits = (int) Math.log10(maxNumberOfTrees) + 1;
-
-        String currentTreeNumberString = Integer.toString(currentTreeNumber);
-        final StringBuilder builder = new StringBuilder();
-
-        for(int i=0; i<numDigits-currentTreeNumberString.length(); i++){
-            builder.append('0');
-        }
-        builder.append(currentTreeNumberString);
-
-        return builder.toString();
-    }
-
 }