diff --git a/src/Plugin/Field/FieldType/ViewsReferenceItem.php b/src/Plugin/Field/FieldType/ViewsReferenceItem.php
index e39431c..d076814 100644
--- a/src/Plugin/Field/FieldType/ViewsReferenceItem.php
+++ b/src/Plugin/Field/FieldType/ViewsReferenceItem.php
@@ -143,6 +143,10 @@ PreconfiguredFieldUiOptionsInterface {
     if (isset($values['target_id']) && is_array($values['target_id'])) {
       $values['target_id'] = isset($values['target_id'][0]['target_id']) ? $values['target_id'][0]['target_id'] : NULL;
     }
+    // Empty string argument only possible if no argument supplied.
+    if ($values['argument'] === '') {
+      $values['argument'] = NULL;
+    }
     parent::setValue($values, FALSE);
 
   }