diff --git a/core/modules/content_translation/src/Plugin/migrate/source/d6/BoxTranslation.php b/core/modules/content_translation/src/Plugin/migrate/source/d6/BoxTranslation.php
index b056801694..1cc1e8961a 100644
--- a/core/modules/content_translation/src/Plugin/migrate/source/d6/BoxTranslation.php
+++ b/core/modules/content_translation/src/Plugin/migrate/source/d6/BoxTranslation.php
@@ -26,8 +26,10 @@ public function query() {
     $query = $this->select('boxes', 'b')
       ->fields('b', ['bid', 'format', 'body'])
       ->fields('i18n', ['property'])
-      ->fields('lt', ['translation', 'language'])
-      ->orderBy('b.bid');
+      ->fields('lt', ['lid', 'translation', 'language'])
+      ->orderBy('b.bid')
+      ->isNotNull('lt.lid');
+
     // Use 'title' for the info field to match the property name in the
     // i18n_strings table.
     $query->addField('b', 'info', 'title');
@@ -36,7 +38,6 @@ public function query() {
     // so PostgreSQL can make the join.
     $query->leftJoin('i18n_strings', 'i18n', 'i18n.objectid = CAST(b.bid as CHAR(255))');
     $query->condition('i18n.type', 'block');
-    $query->isNotNull('i18n.lid');
 
     // Add in the translation for the property.
     $query->leftJoin('locales_target', 'lt', 'lt.lid = i18n.lid');