diff --git a/Models/NullSolution.php b/Models/NullSolution.php
index c692e85..fff8da3 100755
--- a/Models/NullSolution.php
+++ b/Models/NullSolution.php
@@ -34,6 +34,7 @@ final class NullSolution extends Solution
     public function __construct(int $id = 0)
     {
         $this->id = $id;
+        parent::__construct();
     }
 
     /**
diff --git a/Models/Solution.php b/Models/Solution.php
index 610dcc3..ce18ed1 100755
--- a/Models/Solution.php
+++ b/Models/Solution.php
@@ -56,6 +56,11 @@ class Solution
 
     public Risk $risk;
 
+    /**
+     * Constructor.
+     *
+     * @since 1.0.0
+     */
     public function __construct()
     {
         $this->risk = new Risk();