diff --git a/src/MadeYourDay/Contao/Slider.php b/src/MadeYourDay/Contao/Slider.php
index 2652538..64d16cf 100644
--- a/src/MadeYourDay/Contao/Slider.php
+++ b/src/MadeYourDay/Contao/Slider.php
@@ -54,7 +54,7 @@ public function toggleVisibility($intId, $blnVisible)
 		if (is_array($GLOBALS['TL_DCA']['tl_rocksolid_slide']['fields']['published']['save_callback'])) {
 			foreach ($GLOBALS['TL_DCA']['tl_rocksolid_slide']['fields']['published']['save_callback'] as $callback) {
 				$this->import($callback[0]);
-				$blnVisible = $this->$callback[0]->$callback[1]($blnVisible, $this);
+				$blnVisible = $this->{$callback[0]}->{$callback[1]}($blnVisible, $this);
 			}
 		}