diff --git a/mailpoet/lib/Automation/Engine/Control/TriggerHandler.php b/mailpoet/lib/Automation/Engine/Control/TriggerHandler.php
index 03bc7de96d..6f59f73405 100644
--- a/mailpoet/lib/Automation/Engine/Control/TriggerHandler.php
+++ b/mailpoet/lib/Automation/Engine/Control/TriggerHandler.php
@@ -55,8 +55,8 @@ class TriggerHandler {
 
       // ensure subjects are registered and loadable
       $loadedSubjects = [];
-      foreach ($subjects as $key => $args) {
-        $loadedSubjects[] = $this->subjectLoader->loadSubject($key, $args);
+      foreach ($subjects as $subject) {
+        $loadedSubjects[] = $this->subjectLoader->loadSubject($subject['key'], $subject['args']);
       }
 
       $workflowRun = new WorkflowRun($workflow->getId(), $trigger->getKey(), $loadedSubjects);
diff --git a/mailpoet/lib/Automation/Engine/Storage/WorkflowRunStorage.php b/mailpoet/lib/Automation/Engine/Storage/WorkflowRunStorage.php
index ba23372273..92002472c3 100644
--- a/mailpoet/lib/Automation/Engine/Storage/WorkflowRunStorage.php
+++ b/mailpoet/lib/Automation/Engine/Storage/WorkflowRunStorage.php
@@ -42,11 +42,9 @@ class WorkflowRunStorage {
 
     if ($result) {
       $data = (array)$result;
-      $subjects = [];
-      foreach (Json::decode($data['subjects']) as $key => $args) {
-        $subjects[$key] = $this->subjectLoader->loadSubject($key, $args);
-      }
-      $data['subjects'] = $subjects;
+      $data['subjects'] = array_map(function (array $subject) {
+        return $this->subjectLoader->loadSubject($subject['key'], $subject['args']);
+      }, Json::decode($data['subjects']));
       return WorkflowRun::fromArray($data);
     }
     return null;
diff --git a/mailpoet/lib/Automation/Engine/Workflows/WorkflowRun.php b/mailpoet/lib/Automation/Engine/Workflows/WorkflowRun.php
index c1326bf87e..d393e4249e 100644
--- a/mailpoet/lib/Automation/Engine/Workflows/WorkflowRun.php
+++ b/mailpoet/lib/Automation/Engine/Workflows/WorkflowRun.php
@@ -76,7 +76,14 @@ class WorkflowRun {
   }
 
   /** @return Subject[] */
-  public function getSubjects(): array {
+  public function getSubjects(string $key = null): array {
+    if ($key) {
+      return array_values(
+        array_filter($this->subjects, function (Subject $subject) use ($key) {
+          return $subject->getKey() === $key;
+        })
+      );
+    }
     return $this->subjects;
   }
 
@@ -88,10 +95,9 @@ class WorkflowRun {
       'created_at' => $this->createdAt->format(DateTimeImmutable::W3C),
       'updated_at' => $this->updatedAt->format(DateTimeImmutable::W3C),
       'subjects' => Json::encode(
-        array_reduce($this->subjects, function (array $subjects, Subject $subject): array {
-          $subjects[$subject->getKey()] = $subject->pack();
-          return $subjects;
-        }, [])
+        array_map(function (Subject $subject): array {
+          return ['key' => $subject->getKey(), 'args' => $subject->pack()];
+        }, $this->subjects)
       ),
     ];
   }
diff --git a/mailpoet/lib/Automation/Integrations/MailPoet/Actions/SendWelcomeEmailAction.php b/mailpoet/lib/Automation/Integrations/MailPoet/Actions/SendWelcomeEmailAction.php
index eb6fd4163f..3ae96b0bcc 100644
--- a/mailpoet/lib/Automation/Integrations/MailPoet/Actions/SendWelcomeEmailAction.php
+++ b/mailpoet/lib/Automation/Integrations/MailPoet/Actions/SendWelcomeEmailAction.php
@@ -4,6 +4,7 @@ namespace MailPoet\Automation\Integrations\MailPoet\Actions;
 
 use MailPoet\Automation\Engine\Workflows\Action;
 use MailPoet\Automation\Engine\Workflows\Step;
+use MailPoet\Automation\Engine\Workflows\Subject;
 use MailPoet\Automation\Engine\Workflows\Workflow;
 use MailPoet\Automation\Engine\Workflows\WorkflowRun;
 use MailPoet\Automation\Integrations\MailPoet\Subjects\SegmentSubject;
@@ -61,16 +62,20 @@ class SendWelcomeEmailAction implements Action {
     } catch (InvalidStateException $exception) {
       return false;
     }
-    
-    $segmentSubject = $subjects['mailpoet:segment'] ?? null;
-    $subscriberSubject = $subjects['mailpoet:subscriber'] ?? null;
 
-    return $segmentSubject instanceof SegmentSubject && $subscriberSubject instanceof SubscriberSubject;
+    $segmentSubjects = array_filter($subjects, function (Subject $subject) {
+      return $subject->getKey() === SegmentSubject::KEY;
+    });
+    $subscriberSubjects = array_filter($subjects, function (Subject $subject) {
+      return $subject->getKey() === SubscriberSubject::KEY;
+    });
+
+    return count($segmentSubjects) === 1 && count($subscriberSubjects) === 1;
   }
 
   public function run(Workflow $workflow, WorkflowRun $workflowRun, Step $step): void {
     $newsletter = $this->getWelcomeEmailForStep($step);
-    $subscriberSubject = $workflowRun->getSubjects()['mailpoet:subscriber'] ?? null;
+    $subscriberSubject = $workflowRun->getSubjects('mailpoet:subscriber')[0] ?? null;
     if (!$subscriberSubject instanceof SubscriberSubject) {
       throw InvalidStateException::create()->withMessage('A mailpoet:subscriber subject is required.');
     }
@@ -86,7 +91,7 @@ class SendWelcomeEmailAction implements Action {
       throw InvalidStateException::create()->withMessage(sprintf("Cannot schedule a newsletter for subscriber ID '%s' because their status is '%s'.", $subscriber->getId(), $subscriber->getStatus()));
     }
 
-    $segmentSubject = $workflowRun->getSubjects()['mailpoet:segment'] ?? null;
+    $segmentSubject = $workflowRun->getSubjects('mailpoet:segment')[0] ?? null;
     if (!$segmentSubject instanceof SegmentSubject) {
       throw InvalidStateException::create()->withMessage('A mailpoet:segment subject is required.');
     }
@@ -119,7 +124,7 @@ class SendWelcomeEmailAction implements Action {
         ->withErrors($errors);
     }
   }
-  
+
   private function getWelcomeEmailForStep(Step $step): NewsletterEntity {
     $welcomeEmailId = $step->getArgs()['welcomeEmailId'] ?? null;
     if ($welcomeEmailId === null) {
diff --git a/mailpoet/lib/Automation/Integrations/MailPoet/Triggers/SegmentSubscribedTrigger.php b/mailpoet/lib/Automation/Integrations/MailPoet/Triggers/SegmentSubscribedTrigger.php
index aadc4e0090..efce304620 100644
--- a/mailpoet/lib/Automation/Integrations/MailPoet/Triggers/SegmentSubscribedTrigger.php
+++ b/mailpoet/lib/Automation/Integrations/MailPoet/Triggers/SegmentSubscribedTrigger.php
@@ -41,8 +41,18 @@ class SegmentSubscribedTrigger implements Trigger {
     }
 
     $this->wp->doAction(Hooks::TRIGGER, $this, [
-      SegmentSubject::KEY => ['segment_id' => $segment->getId()],
-      SubscriberSubject::KEY => ['subscriber_id' => $subscriber->getId()],
+      [
+        'key' => SegmentSubject::KEY,
+        'args' => [
+          'segment_id' => $segment->getId(),
+        ],
+      ],
+      [
+        'key' => SubscriberSubject::KEY,
+        'args' => [
+          'subscriber_id' => $subscriber->getId(),
+        ],
+      ],
     ]);
   }
 }