diff --git a/core/modules/migrate/src/Entity/Migration.php b/core/modules/migrate/src/Entity/Migration.php
index 0791750..2c14c3a 100644
--- a/core/modules/migrate/src/Entity/Migration.php
+++ b/core/modules/migrate/src/Entity/Migration.php
@@ -78,6 +78,9 @@ class Migration extends ConfigEntityBase implements MigrationInterface, Requirem
   /**
    * The configuration describing the process plugins.
    *
+   * This is a strictly internal property and should not returned to calling
+   * code, use getProcess() instead.
+   *
    * @var array
    */
   protected $process;
@@ -393,7 +396,7 @@ public function isComplete() {
    * {@inheritdoc}
    */
   public function getProcess() {
-    return $this->process;
+    return $this->getProcessNormalized($this->process);
   }
 
   /**
@@ -408,7 +411,7 @@ public function setProcess(array $process) {
    * {@inheritdoc}
    */
   public function setProcessOfProperty($field_name, $process) {
-    $this->process = $this->getProcessNormalized([$field_name => $process]) + $this->process;
+    $this->process[$field_name] = $process;
     return $this;
   }
 
@@ -418,8 +421,9 @@ public function setProcessOfProperty($field_name, $process) {
   public function mergeProcessOfProperty($field_name, array $process) {
     // If we already have a process value then merge the incoming process array
     //otherwise simply set it.
-    if (isset($this->process[$field_name])) {
-      $this->process = NestedArray::mergeDeepArray([$this->process, $this->getProcessNormalized([$field_name => $process])], TRUE);
+    $current_process = $this->getProcess();
+    if (isset($current_process[$field_name])) {
+      $this->process = NestedArray::mergeDeepArray([$current_process, $this->getProcessNormalized([$field_name => $process])], TRUE);
     }
     else {
       $this->setProcessOfProperty($field_name, $process);