diff --git a/system/src/Grav/Common/Twig/TwigExtension.php b/system/src/Grav/Common/Twig/TwigExtension.php
index f05f502ec..e6f9a53dc 100644
--- a/system/src/Grav/Common/Twig/TwigExtension.php
+++ b/system/src/Grav/Common/Twig/TwigExtension.php
@@ -1420,10 +1420,12 @@ class TwigExtension extends AbstractExtension implements GlobalsInterface
      * @param $classes
      * @return string|string[]|null
      */
-    public static function svgImageFunction($path, $classes)
+    public static function svgImageFunction($path, $classes = null)
     {
         $path = Utils::fullPath($path);
 
+        $classes = $classes ?: '';
+
         if (file_exists($path)) {
             $svg = file_get_contents($path);
             $classes = " inline-block $classes";