diff --git a/src/Collection.php b/src/Collection.php
index 2dd26df..099647a 100644
--- a/src/Collection.php
+++ b/src/Collection.php
@@ -67,6 +67,10 @@ public function toTree($root = false)
             if ($node->getParentId() == $root) {
                 $items[] = $node;
             }
+
+            if($node->isLeaf()){
+                unset($node->children);
+            }
         }
 
         return new static($items);
@@ -140,4 +144,4 @@ protected function flattenTree(self $groupedNodes, $parentId)
         return $this;
     }
 
-}
\ No newline at end of file
+}
diff --git a/src/NestedSet.php b/src/NestedSet.php
index 8ec8e02..2f5ac6a 100644
--- a/src/NestedSet.php
+++ b/src/NestedSet.php
@@ -35,14 +35,16 @@ class NestedSet
      * Add default nested set columns to the table. Also create an index.
      *
      * @param \Illuminate\Database\Schema\Blueprint $table
+     * @param string $idColumn
      */
-    public static function columns(Blueprint $table)
+    public static function columns(Blueprint $table, string $idColumn = 'id')
     {
-        $table->unsignedInteger(self::LFT)->default(0);
-        $table->unsignedInteger(self::RGT)->default(0);
-        $table->unsignedInteger(self::PARENT_ID)->nullable();
+        $table->unsignedBigInteger(self::LFT)->default(0);
+        $table->unsignedBigInteger(self::RGT)->default(0);
+        $table->unsignedBigInteger(self::PARENT_ID)->nullable();
 
         $table->index(static::getDefaultColumns());
+        $table->foreign(self::PARENT_ID)->references($idColumn)->on($table->getTable())->onDelete('cascade');
     }
 
     /**
@@ -54,6 +56,7 @@ public static function dropColumns(Blueprint $table)
     {
         $columns = static::getDefaultColumns();
 
+        $table->dropForeign(self::PARENT_ID);
         $table->dropIndex($columns);
         $table->dropColumn($columns);
     }
@@ -80,4 +83,4 @@ public static function isNode($node)
         return is_object($node) && in_array(NodeTrait::class, (array)$node);
     }
 
-}
\ No newline at end of file
+}
diff --git a/src/NestedSetServiceProvider.php b/src/NestedSetServiceProvider.php
index b4516f7..740ef54 100644
--- a/src/NestedSetServiceProvider.php
+++ b/src/NestedSetServiceProvider.php
@@ -9,12 +9,12 @@ class NestedSetServiceProvider extends ServiceProvider
 {
     public function register()
     {
-        Blueprint::macro('nestedSet', function () {
-            NestedSet::columns($this);
+        Blueprint::macro('nestedSet', function (string $idColumn = 'id') {
+            NestedSet::columns($this, $idColumn);
         });
 
         Blueprint::macro('dropNestedSet', function () {
             NestedSet::dropColumns($this);
         });
     }
-}
\ No newline at end of file
+}