diff --git a/includes/CommentModifier.php b/includes/CommentModifier.php
index 2c00693d9..d6d56c88d 100644
--- a/includes/CommentModifier.php
+++ b/includes/CommentModifier.php
@@ -2,6 +2,7 @@
 
 namespace MediaWiki\Extension\DiscussionTools;
 
+use DOMDocument;
 use DOMElement;
 use DOMNode;
 use stdClass;
@@ -290,11 +291,13 @@ class CommentModifier {
 
 	/**
 	 * Create an element that will convert to the provided wikitext
+	 *
+	 * @param DOMDocument $doc Document
 	 * @param string $wt Wikitext
 	 * @return DOMElement Element
 	 */
-	public static function createWikitextNode( string $wt ) : DOMElement {
-		$span = $document->createElement( 'span' );
+	public static function createWikitextNode( DOMDocument $doc, string $wt ) : DOMElement {
+		$span = $doc->createElement( 'span' );
 
 		$span->setAttribute( 'typeof', 'mw:Transclusion' );
 		$span->setAttribute( 'data-mw', json_encode( [ 'parts' => [ $wt ] ] ) );
diff --git a/modules/CommentController.js b/modules/CommentController.js
index 19f98f862..c56e1db45 100644
--- a/modules/CommentController.js
+++ b/modules/CommentController.js
@@ -258,7 +258,7 @@ CommentController.prototype.postReply = function ( parsoidData ) {
 		wikitext = controller.sanitizeWikitextLinebreaks( controller.autoSignWikitext( wikitext ) );
 		wikitext.split( '\n' ).forEach( function ( line ) {
 			var p = doc.createElement( 'p' );
-			p.appendChild( modifier.createWikitextNode( line ) );
+			p.appendChild( modifier.createWikitextNode( doc, line ) );
 			container.appendChild( p );
 		} );
 	} else {
@@ -271,7 +271,7 @@ CommentController.prototype.postReply = function ( parsoidData ) {
 		// Sign the last line
 		// TODO: Check if the user tried to sign in visual mode by typing wikitext?
 		// TODO: When we implement posting new topics, the leading space will create an indent-pre
-		container.lastChild.appendChild( modifier.createWikitextNode( ' ~~~~' ) );
+		container.lastChild.appendChild( modifier.createWikitextNode( doc, ' ~~~~' ) );
 	}
 
 	// Transfer comment DOM to Parsoid DOM
diff --git a/modules/modifier.js b/modules/modifier.js
index da27aa335..9492ff961 100644
--- a/modules/modifier.js
+++ b/modules/modifier.js
@@ -253,8 +253,8 @@ function addSiblingListItem( previousItem ) {
 	return listItem;
 }
 
-function createWikitextNode( wt ) {
-	var span = document.createElement( 'span' );
+function createWikitextNode( doc, wt ) {
+	var span = doc.createElement( 'span' );
 
 	span.setAttribute( 'typeof', 'mw:Transclusion' );
 	span.setAttribute( 'data-mw', JSON.stringify( { parts: [ wt ] } ) );