diff --git a/src/View/Form/NullContext.php b/src/View/Form/NullContext.php
index cc90f7e5699..9dfce7cbc55 100644
--- a/src/View/Form/NullContext.php
+++ b/src/View/Form/NullContext.php
@@ -52,7 +52,7 @@ public function primaryKey() {
 /**
  * {@inheritDoc}
  */
-	public function isPrimaryKey() {
+	public function isPrimaryKey($field) {
 		return false;
 	}