diff --git a/core/modules/comment/tests/src/Kernel/Migrate/d6/MigrateCommentTest.php b/core/modules/comment/tests/src/Kernel/Migrate/d6/MigrateCommentTest.php
index 69f8de8..1614163 100644
--- a/core/modules/comment/tests/src/Kernel/Migrate/d6/MigrateCommentTest.php
+++ b/core/modules/comment/tests/src/Kernel/Migrate/d6/MigrateCommentTest.php
@@ -61,7 +61,7 @@ public function testComments() {
     $this->assertIdentical('The first comment.', $comment->getSubject());
     $this->assertIdentical('The first comment body.', $comment->comment_body->value);
     $this->assertIdentical('filtered_html', $comment->comment_body->format);
-    $this->assertIdentical('0', $comment->pid->target_id);
+    $this->assertIdentical(NULL, $comment->pid->target_id);
     $this->assertIdentical('1', $comment->getCommentedEntityId());
     $this->assertIdentical('node', $comment->getCommentedEntityTypeId());
     $this->assertIdentical('en', $comment->language()->getId());
@@ -73,6 +73,6 @@ public function testComments() {
 
     $comment = $comment_storage->load(3);
     $this->assertIdentical('The second comment.', $comment->subject->value);
-    $this->assertIdentical('0', $comment->pid->target_id);
+    $this->assertIdentical(NULL, $comment->pid->target_id);
   }
 }
diff --git a/core/modules/migrate/src/MigrateExecutable.php b/core/modules/migrate/src/MigrateExecutable.php
index 07231a9..42a1396 100644
--- a/core/modules/migrate/src/MigrateExecutable.php
+++ b/core/modules/migrate/src/MigrateExecutable.php
@@ -383,6 +383,7 @@ public function processRow(Row $row, array $process = NULL, $value = NULL) {
               $new_value[] = $plugin->transform($scalar_value, $this, $row, $destination);
             }
             catch (MigrateSkipProcessException $e) {
+              $new_value[] = NULL;
               $break = TRUE;
             }
           }
@@ -396,6 +397,7 @@ public function processRow(Row $row, array $process = NULL, $value = NULL) {
             $value = $plugin->transform($value, $this, $row, $destination);
           }
           catch (MigrateSkipProcessException $e) {
+            $value = NULL;
             break;
           }
           $multiple = $multiple || $plugin->multiple();