diff --git a/core/modules/migrate/src/Annotation/MigrateSource.php b/core/modules/migrate/src/Annotation/MigrateSource.php
index 349bcf8..95a2431 100644
--- a/core/modules/migrate/src/Annotation/MigrateSource.php
+++ b/core/modules/migrate/src/Annotation/MigrateSource.php
@@ -81,7 +81,10 @@ public function getProvider() {
    */
   public function getProviders() {
     if (isset($this->definition['provider'])) {
-      return is_array($this->definition['provider']) ? $this->definition['provider'] : [$this->definition['provider']];
+      // Ensure that we return an array even if
+      // \Drupal\Component\Annotation\AnnotationInterface::setProvider() has
+      // been called.
+      return (array) $this->definition['provider'];
     }
     return [];
   }
diff --git a/core/modules/migrate/src/Plugin/Discovery/AnnotatedClassDiscoveryAutomatedProviders.php b/core/modules/migrate/src/Plugin/Discovery/AnnotatedClassDiscoveryAutomatedProviders.php
index 8a53db4..967569c 100644
--- a/core/modules/migrate/src/Plugin/Discovery/AnnotatedClassDiscoveryAutomatedProviders.php
+++ b/core/modules/migrate/src/Plugin/Discovery/AnnotatedClassDiscoveryAutomatedProviders.php
@@ -73,7 +73,7 @@ protected function prepareAnnotationDefinition(AnnotationInterface $annotation,
     $providers = array_unique(array_filter($providers, function ($provider) {
       return $provider && $provider !== 'component';
     }));
-    $annotation->setProviders(array_unique(array_filter($providers)));
+    $annotation->setProviders($providers);
   }
 
   /**