diff --git a/mathjax3-ts/adaptors/lite/Parser.ts b/mathjax3-ts/adaptors/lite/Parser.ts
index 8efc37965..872844a46 100644
--- a/mathjax3-ts/adaptors/lite/Parser.ts
+++ b/mathjax3-ts/adaptors/lite/Parser.ts
@@ -356,6 +356,9 @@ export class LiteParser implements MinDOMParser<LiteDocument> {
      * @return {string}      The string with " replaced by entities
      */
     public protectAttribute(text: string) {
+        if (typeof text !== 'string') {
+            text = String(text);
+        }
         return text.replace(/"/, '&quot;');
     }