diff --git a/system/HTTP/Files/UploadedFile.php b/system/HTTP/Files/UploadedFile.php
index 0626aeb5581f..a566fa7f67c7 100644
--- a/system/HTTP/Files/UploadedFile.php
+++ b/system/HTTP/Files/UploadedFile.php
@@ -302,7 +302,8 @@ public function getTempName(): string
      */
     public function getExtension(): string
     {
-        return ! in_array($this->guessExtension(), ['', '0'], true) ? $this->guessExtension() : $this->getClientExtension();
+        $guessExtension = $this->guessExtension();
+        return $guessExtension !== '' ? $guessExtension : $this->getClientExtension();
     }
 
     /**