diff --git a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Comment.php b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Comment.php
index b68c27d..621dc56 100644
--- a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Comment.php
+++ b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Comment.php
@@ -37,7 +37,7 @@ public function query() {
   /**
    * {@inheritdoc}
    */
-  public function prepareRow(Row $row, $keep = TRUE) {
+  public function prepareRow(Row $row) {
     if ($this->variableGet('comment_subject_field_' . $row->getSourceProperty('type'), 1)) {
       // Comment subject visible.
       $row->setSourceProperty('field_name', 'comment');
@@ -72,7 +72,7 @@ public function fields() {
       'name' => $this->t("The comment author's name. Uses {users}.name if the user is logged in, otherwise uses the value typed into the comment form."),
       'mail' => $this->t("The comment author's email address from the comment form, if user is anonymous, and the 'Anonymous users may/must leave their contact information' setting is turned on."),
       'homepage' => $this->t("The comment author's home page address from the comment form, if user is anonymous, and the 'Anonymous users may/must leave their contact information' setting is turned on."),
-      'type' => $this->t("The {node}.type to which this comment is a reply.")
+      'type' => $this->t("The {node}.type to which this comment is a reply."),
     );
   }
 
diff --git a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Field.php b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Field.php
index 542fde2..3738dce 100644
--- a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Field.php
+++ b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Field.php
@@ -68,7 +68,7 @@ public function fields() {
   /**
    * {@inheritdoc}
    */
-  public function prepareRow(Row $row, $keep = TRUE) {
+  public function prepareRow(Row $row) {
     // Unserialize data.
     $global_settings = unserialize($row->getSourceProperty('global_settings'));
     $widget_settings = unserialize($row->getSourceProperty('widget_settings'));
diff --git a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/FieldInstance.php b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/FieldInstance.php
index e6f4721..35d2ecf 100644
--- a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/FieldInstance.php
+++ b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/FieldInstance.php
@@ -72,7 +72,7 @@ public function fields() {
   /**
    * {@inheritdoc}
    */
-  public function prepareRow(Row $row, $keep = TRUE) {
+  public function prepareRow(Row $row) {
     // Unserialize data.
     $widget_settings = unserialize($row->getSourceProperty('widget_settings'));
     $display_settings = unserialize($row->getSourceProperty('display_settings'));
diff --git a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Role.php b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Role.php
index 754d6cd..5ba763f 100644
--- a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Role.php
+++ b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Role.php
@@ -67,7 +67,7 @@ protected function runQuery() {
   /**
    * {@inheritdoc}
    */
-  public function prepareRow(Row $row, $keep = TRUE) {
+  public function prepareRow(Row $row) {
     $rid = $row->getSourceProperty('rid');
     $permissions = $this->select('permission', 'p')
       ->fields('p', array('perm'))
diff --git a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/User.php b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/User.php
index 058f7ed..333765a 100644
--- a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/User.php
+++ b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/User.php
@@ -52,7 +52,7 @@ public function fields() {
   /**
    * {@inheritdoc}
    */
-  public function prepareRow(Row $row, $keep = TRUE) {
+  public function prepareRow(Row $row) {
     // User roles.
     $roles = $this->select('users_roles', 'ur')
       ->fields('ur', array('rid'))