diff --git a/api/src/Etemplate/Widget/Customfields.php b/api/src/Etemplate/Widget/Customfields.php
index 466ff5f5bc..51c975e7a0 100644
--- a/api/src/Etemplate/Widget/Customfields.php
+++ b/api/src/Etemplate/Widget/Customfields.php
@@ -405,7 +405,7 @@ class Customfields extends Transformer
 		$all_readonly = $this->is_readonly($cname, $form_name);
 		$value_in = self::get_array($content, $form_name);
 		// if we have no id / use self::GLOBAL_ID, we have to set $value_in in global namespace for regular widgets validation to find
-		if (!$this->id) $content = array_merge($content, $value_in);
+		if (!$this->id) $content = array_merge($content, (array)$value_in);
 		//error_log(__METHOD__."($cname, ...) form_name=$form_name, use-private={$this->attrs['use-private']}, value_in=".array2string($value_in));
 		if($this->getElementAttribute($form_name, 'customfields'))
 		{