diff --git a/src/fields/ColourSwatches.php b/src/fields/ColourSwatches.php
index 3576666..1add104 100644
--- a/src/fields/ColourSwatches.php
+++ b/src/fields/ColourSwatches.php
@@ -151,7 +151,7 @@ public function serializeValue(mixed $value, ?ElementInterface $element = null):
             if ($value && ($palette["label"] === $value['label'])) {
                 $saveValue = $value;
                 $saveValue['color'] = $palette['color'];
-                $saveValue['class'] = $palette['class'];
+                $saveValue['class'] = $palette['class'] ?? '';
             }
         }