diff --git a/lib/Service/Importer/Systems/TrelloJsonService.php b/lib/Service/Importer/Systems/TrelloJsonService.php
index a4a3673c1..71c897cec 100644
--- a/lib/Service/Importer/Systems/TrelloJsonService.php
+++ b/lib/Service/Importer/Systems/TrelloJsonService.php
@@ -332,7 +332,7 @@ public function getAclList(): array {
 		return $return;
 	}
 
-	private function translateColor(string $color): string {
+	private function translateColor(?string $color): string {
 		switch ($color) {
 			case 'red':
 				return 'ff0000';