diff --git a/publi_bib.php b/publi_bib.php
index e5431c6..e53588c 100644
--- a/publi_bib.php
+++ b/publi_bib.php
@@ -123,7 +123,9 @@ $listener->addProcessor(new Processor\TagNameCaseProcessor(CASE_LOWER));
 $listener->addProcessor(new NamesProcessor());
 $listener->addProcessor(static function (array $entry) {
     $entry['title'] = removeBoundingBraces($entry['title']);
-    $entry['journal'] = expandJournalReferences($entry['journal']);
+    if (isset($entry['journal'])) {
+      $entry['journal'] = expandJournalReferences($entry['journal']);
+    }
     return $entry;
 });