diff --git a/core/modules/taxonomy/src/Plugin/migrate/source/d6/I18nTaxonomyVocabulary.php b/core/modules/taxonomy/src/Plugin/migrate/source/d6/I18nTaxonomyVocabulary.php
index 1a102a9..664849f 100644
--- a/core/modules/taxonomy/src/Plugin/migrate/source/d6/I18nTaxonomyVocabulary.php
+++ b/core/modules/taxonomy/src/Plugin/migrate/source/d6/I18nTaxonomyVocabulary.php
@@ -38,7 +38,9 @@ public function query() {
       ->fields('lt', ['lid', 'translation'])
       ->condition('i18n.type', 'vocabulary');
     $query->addField('lt', 'language', 'language');
-    $query->join('i18n_strings', 'i18n', 'i18n.objectid = v.vid');
+    // The vid is an integer and the objectid is a string. Use the like operator
+    // to force PostgreSQL to cast the vid to a string.
+    $query->join('i18n_strings', 'i18n', 'v.vid like i18n.objectid');
     $query->leftJoin('locales_target', 'lt', 'lt.lid = i18n.lid');
 
     return $query;