diff -u b/src/Importer.php b/src/Importer.php
--- b/src/Importer.php
+++ b/src/Importer.php
@@ -185,24 +185,24 @@
 
       // @todo what if no dependencies?
       $sorted = $this->sortTree($this->graph);
-      $langs_available = array_keys($this->languageManager->getLanguages());
-      $current_lang = $this->languageManager->getCurrentLanguage()->getId();
+      $languages_available = array_keys($this->languageManager->getLanguages());
+      $current_language = $this->languageManager->getCurrentLanguage()->getId();
       foreach ($sorted as $link => $details) {
         if (!empty($file_map[$link])) {
           $file = $file_map[$link];
           $entity_type_id = $file->entity_type_id;
           $class = $this->entityTypeManager->getDefinition($entity_type_id)->getClass();
           $contents = $this->parseFile($file);
-          // Decode check language, if language unavailable set to default language
+          // Decode, check language, enforce supported language on content
           $decoded = $this->serializer->decode($contents, 'hal_json');
-          if (isset($decoded['langcode']) && !in_array($decoded['langcode'][0]['value'], $langs_available)) {
-            $decoded['langcode'][0]['value'] = $current_lang;
+          if (isset($decoded['langcode']) && !in_array($decoded['langcode'][0]['value'], $languages_available), TRUE) {
+            $decoded['langcode'][0]['value'] = $current_language;
           }
           array_walk_recursive($decoded, function (&$value, $key, $userdata) {
-            if (($key == 'lang') && (!in_array($value, $userdata[1]))) {
+            if (($key == 'lang') && (!in_array($value, $userdata[1], TRUE))) {
               $value = $userdata[0];
             }
-          }, [$current_lang, $langs_available]);
+          }, [$current_language, $languages_available]);
           $contents = $this->serializer->encode($decoded, 'hal_json');
           $entity = $this->serializer->deserialize($contents, $class, 'hal_json', ['request_method' => 'POST']);
           $entity->enforceIsNew(TRUE);