diff --git a/includes/CommentModifier.php b/includes/CommentModifier.php
index 60429301c..eec92a844 100644
--- a/includes/CommentModifier.php
+++ b/includes/CommentModifier.php
@@ -291,7 +291,7 @@ class CommentModifier {
 		$hasElements = false;
 		foreach ( $nodes as $node ) {
 			if ( $node instanceof Element ) {
-				if ( strtolower( $node->nodeName ) !== strtolower( $type ) ) {
+				if ( strtolower( $node->tagName ) !== strtolower( $type ) ) {
 					return false;
 				}
 				$hasElements = true;
diff --git a/includes/CommentParser.php b/includes/CommentParser.php
index 4a98e78e6..98f32bcc5 100644
--- a/includes/CommentParser.php
+++ b/includes/CommentParser.php
@@ -598,7 +598,7 @@ class CommentParser {
 				// if the timestamp node is the only child of a link node, use the link node instead
 				//
 				// Handle links nested in formatting elements.
-				if ( $event === 'leave' && $node instanceof Element && strtolower( $node->nodeName ) === 'a' ) {
+				if ( $event === 'leave' && $node instanceof Element && strtolower( $node->tagName ) === 'a' ) {
 					$username = $this->getUsernameFromLink( $node );
 					if ( $username ) {
 						// Accept the first link to the user namespace, then only accept links to that user
diff --git a/includes/CommentUtils.php b/includes/CommentUtils.php
index 3420e71be..d22d53d20 100644
--- a/includes/CommentUtils.php
+++ b/includes/CommentUtils.php
@@ -148,9 +148,9 @@ class CommentUtils {
 	public static function isCommentSeparator( Node $node ): bool {
 		return $node instanceof Element && (
 			// Empty paragraphs (`<p><br></p>`) between indented comments mess up indentation detection
-			strtolower( $node->nodeName ) === 'br' ||
+			strtolower( $node->tagName ) === 'br' ||
 			// Horizontal line
-			strtolower( $node->nodeName ) === 'hr' ||
+			strtolower( $node->tagName ) === 'hr' ||
 			// {{outdent}} templates
 			DOMCompat::getClassList( $node )->contains( 'outdent-template' )
 		);
@@ -213,7 +213,7 @@ class CommentUtils {
 		do {
 			if (
 				$node instanceof Element &&
-				in_array( strtolower( $node->nodeName ), $tagNames )
+				in_array( strtolower( $node->tagName ), $tagNames )
 			) {
 				return $node;
 			}
diff --git a/modules/dt.ui.ReplyWidget.js b/modules/dt.ui.ReplyWidget.js
index 7857be712..84c97725e 100644
--- a/modules/dt.ui.ReplyWidget.js
+++ b/modules/dt.ui.ReplyWidget.js
@@ -40,7 +40,7 @@ function ReplyWidget( commentController, commentDetails, config ) {
 	// don't need to worry about transcluded replies.
 	this.pageExists = mw.config.get( 'wgRelevantArticleId', 0 ) !== 0;
 	var contextNode = utils.closestElement( threadItem.range.endContainer, [ 'dl', 'ul', 'ol' ] );
-	this.context = contextNode ? contextNode.nodeName.toLowerCase() : 'dl';
+	this.context = contextNode ? contextNode.tagName.toLowerCase() : 'dl';
 	// TODO: Should storagePrefix include pageName?
 	this.storagePrefix = 'reply/' + threadItem.id;
 	this.storage = controller.storage;
diff --git a/modules/utils.js b/modules/utils.js
index d01fe392b..d5c61a6a0 100644
--- a/modules/utils.js
+++ b/modules/utils.js
@@ -113,9 +113,9 @@ function cantHaveElementChildren( node ) {
 function isCommentSeparator( node ) {
 	return node.nodeType === Node.ELEMENT_NODE && (
 		// Empty paragraphs (`<p><br></p>`) between indented comments mess up indentation detection
-		node.nodeName.toLowerCase() === 'br' ||
+		node.tagName.toLowerCase() === 'br' ||
 		// Horizontal line
-		node.nodeName.toLowerCase() === 'hr' ||
+		node.tagName.toLowerCase() === 'hr' ||
 		// {{outdent}} templates
 		node.classList.contains( 'outdent-template' )
 	);