diff --git a/src/Traits/Getter.php b/src/Traits/Getter.php
index ca65baf..3aa4161 100644
--- a/src/Traits/Getter.php
+++ b/src/Traits/Getter.php
@@ -43,12 +43,12 @@ trait Getter
     {
         $method = '_get' . ucfirst($property);
         if (
-            property_exists(__CLASS__, $property)
-            && method_exists(__CLASS__, $method)
+            property_exists(get_called_class(), $property)
+            && method_exists(get_called_class(), $method)
         ) {
             return $this->$method();
         } else {
-            throw new \InvalidArgumentException('Invalid property or missing getter method for property "' . __CLASS__ . '->' . $property . '".');
+            throw new \InvalidArgumentException('Invalid property or missing getter method for property "' . get_called_class() . '->' . $property . '".');
         }
     }
 
diff --git a/src/Traits/Setter.php b/src/Traits/Setter.php
index 3da6171..1bd8652 100644
--- a/src/Traits/Setter.php
+++ b/src/Traits/Setter.php
@@ -44,12 +44,12 @@ trait Setter
     {
         $method = '_set' . ucfirst($property);
         if (
-            property_exists(__CLASS__, $property)
-            && method_exists(__CLASS__, $method)
+            property_exists(get_called_class(), $property)
+            && method_exists(get_called_class(), $method)
         ) {
             $this->$method($value);
         } else {
-            throw new \InvalidArgumentException('Invalid property or missing setter method for property "' . __CLASS__ . '->' . $property . '".');
+            throw new \InvalidArgumentException('Invalid property or missing setter method for property "' . get_called_class() . '->' . $property . '".');
         }
     }
 
diff --git a/src/Traits/Singleton.php b/src/Traits/Singleton.php
index 0c4a6b9..593222c 100644
--- a/src/Traits/Singleton.php
+++ b/src/Traits/Singleton.php
@@ -40,11 +40,11 @@ trait Singleton
      */
     final public static function getInstance(): self
     {
-        if (!isset(self::$singleton)) {
-            $reflectionClass = new \ReflectionClass(__CLASS__);
-            self::$instance = $reflectionClass->newInstanceArgs(func_get_args());
+        if (!isset(static::$singleton)) {
+            $reflectionClass = new \ReflectionClass(get_called_class());
+            static::$singleton = $reflectionClass->newInstanceArgs(func_get_args());
         }
-        return self::$singleton;
+        return static::$singleton;
     }
 
     /**