diff --git a/src/Traits/Getter.php b/src/Traits/Getter.php
index 184d568..dd0a2fa 100644
--- a/src/Traits/Getter.php
+++ b/src/Traits/Getter.php
@@ -45,12 +45,12 @@ trait Getter
     {
         $method = 'magicGet' . ucfirst($property);
         if (
-            property_exists(get_called_class(), $property)
-            && method_exists(get_called_class(), $method)
+            property_exists(static::class, $property)
+            && method_exists(static::class, $method)
         ) {
             return $this->$method();
         } else {
-            throw new InvalidArgumentException('Invalid property or missing getter method for property: ' . get_called_class() . '->' . $property . '.');
+            throw new InvalidArgumentException('Invalid property or missing getter method for property: ' . static::class . '->' . $property . '.');
         }
     }
 
diff --git a/src/Traits/Setter.php b/src/Traits/Setter.php
index a1d8734..a316a34 100644
--- a/src/Traits/Setter.php
+++ b/src/Traits/Setter.php
@@ -46,12 +46,12 @@ trait Setter
     {
         $method = 'magicSet' . ucfirst($property);
         if (
-            property_exists(get_called_class(), $property)
-            && method_exists(get_called_class(), $method)
+            property_exists(static::class, $property)
+            && method_exists(static::class, $method)
         ) {
             $this->$method($value);
         } else {
-            throw new InvalidArgumentException('Invalid property or missing setter method for property: ' . get_called_class() . '->' . $property . '.');
+            throw new InvalidArgumentException('Invalid property or missing setter method for property: ' . static::class . '->' . $property . '.');
         }
     }
 
diff --git a/src/Traits/Singleton.php b/src/Traits/Singleton.php
index 2379c84..8e0da1b 100644
--- a/src/Traits/Singleton.php
+++ b/src/Traits/Singleton.php
@@ -40,20 +40,22 @@ trait Singleton
      *
      * @param mixed ...$args Parameters for the constructor
      */
-    public static function getInstance(mixed ...$args): self
+    final public static function getInstance(mixed ...$args): static
     {
         $class = static::class;
         if (!isset(static::$singleton[$class])) {
-            static::$singleton[$class] = new $class(...$args);
+            static::$singleton[$class] = new static(...$args);
         }
         return static::$singleton[$class];
     }
 
     /**
-     * This is a singleton class, thus the constructor is protected.
+     * This is a singleton class, thus the constructor is private.
      * (Get an instance of this class by calling self::getInstance())
+     *
+     * @param mixed ...$args Parameters for the constructor
      */
-    abstract protected function __construct();
+    abstract private function __construct(mixed ...$args);
 
     /**
      * This is a singleton class, thus cloning is prohibited.