diff --git a/server/providers/OpenLibrary.js b/server/providers/OpenLibrary.js
index 453c919b..10d03378 100644
--- a/server/providers/OpenLibrary.js
+++ b/server/providers/OpenLibrary.js
@@ -66,10 +66,10 @@ class OpenLibrary {
   }
 
   parsePublishYear(doc, worksData) {
-    if (doc.first_publish_year && !isNaN(doc.first_publish_year)) return doc.first_publish_year
+    if (doc.first_publish_year && !isNaN(doc.first_publish_year)) return String(doc.first_publish_year)
     if (worksData.first_publish_date) {
       var year = worksData.first_publish_date.split('-')[0]
-      if (!isNaN(year)) return year
+      if (!isNaN(year)) return String(year)
     }
     return null
   }