diff --git a/src/QUI/Bricks/Brick.php b/src/QUI/Bricks/Brick.php
index 5193a5f1708d54bec6a8c0e8bb5780015ba49e82..83fe60d3e52576c8aeba0f888d6633004471432d 100644
--- a/src/QUI/Bricks/Brick.php
+++ b/src/QUI/Bricks/Brick.php
@@ -573,7 +573,7 @@ public function getCustomFields()
     public function addCSSClass($cssClass)
     {
         if (\is_array($cssClass)) {
-            $cssClass = \implode($cssClass, ' ');
+            $cssClass = \implode(' ', $cssClass);
         }
 
         if (!\is_string($cssClass)) {