diff --git a/src/static/js/ace2_inner.js b/src/static/js/ace2_inner.js
index 95db2c14f..60b029f3b 100644
--- a/src/static/js/ace2_inner.js
+++ b/src/static/js/ace2_inner.js
@@ -1139,7 +1139,7 @@ function Ace2Inner() {
 
       lastDirtyNode = (lastDirtyNode && isNodeDirty(lastDirtyNode) && lastDirtyNode);
       if (firstDirtyNode && lastDirtyNode) {
-        const cc = makeContentCollector(isStyled, browser, rep.apool, null, className2Author);
+        const cc = makeContentCollector(isStyled, browser, rep.apool, className2Author);
         cc.notifySelection(selection);
         const dirtyNodes = [];
         for (let n = firstDirtyNode; n &&
diff --git a/src/static/js/contentcollector.js b/src/static/js/contentcollector.js
index ab5781725..a77c4e5f0 100644
--- a/src/static/js/contentcollector.js
+++ b/src/static/js/contentcollector.js
@@ -32,8 +32,8 @@ const hooks = require('./pluginfw/hooks');
 
 const sanitizeUnicode = (s) => UNorm.nfc(s);
 
-const makeContentCollector = (collectStyles, abrowser, apool, domInterface, className2Author) => {
-  const dom = domInterface || {
+const makeContentCollector = (collectStyles, abrowser, apool, className2Author) => {
+  const dom = {
     isNodeText: (n) => n.nodeType === 3,
     nodeTagName: (n) => n.tagName,
     nodeValue: (n) => n.nodeValue,