diff --git a/ext/mixed/js/display.js b/ext/mixed/js/display.js
index 82385bf9..4c698ecf 100644
--- a/ext/mixed/js/display.js
+++ b/ext/mixed/js/display.js
@@ -98,7 +98,7 @@ class Display {
         }
     }
 
-    async onTermLookup(e, {disableScroll, selectText, disableHistory}) {
+    async onTermLookup(e, {disableScroll, selectText, disableHistory}={}) {
         const termLookupResults = await this.termLookup(e);
         if (!termLookupResults) {
             return false;