diff --git a/lib/Marcxml.js b/lib/Marcxml.js
index f178b8a..8239d01 100644
--- a/lib/Marcxml.js
+++ b/lib/Marcxml.js
@@ -70,7 +70,7 @@ class Marcxml extends Duplex {
         for (let i = 2; i < element.length; i += 2) {
           doc.push(
             `    <subfield code="${element[i]}">`,
-            he.encode(element[i + 1]),
+            he.encode(element[i + 1]+""),
             '</subfield>\n',
           );
         }