diff --git a/src/Classes/SimpleImage.php b/src/Classes/SimpleImage.php
index e51a660..3206558 100644
--- a/src/Classes/SimpleImage.php
+++ b/src/Classes/SimpleImage.php
@@ -38,7 +38,7 @@ public function __construct($image = null) {
     // Destroys the image resource
     //
     public function __destruct() {
-        if($this->image !== null && get_resource_type($this->image) === 'gd') {
+          if(is_object($this->image) && $this->image instanceof \GDImage) {
             imagedestroy($this->image);
         }
     }
@@ -1797,4 +1797,4 @@ public static function normalizeColor($color) {
         throw new \Exception("Invalid color value: $color", self::ERR_INVALID_COLOR);
     }
 
-}
\ No newline at end of file
+}