--- a/devtools/client/inspector/markup/markup.js
+++ b/devtools/client/inspector/markup/markup.js
@@ -894,19 +894,19 @@ MarkupView.prototype = {
 
           // If we can't move as the user wants, we move to the other direction.
           // If there is no sibling elements anymore, move to the parent node.
           if (!focusNode) {
             focusNode = nextSibling || prevSibling || parent;
           }
 
           let isNextSiblingText = nextSibling ?
-            nextSibling.nodeType === Ci.nsIDOMNode.TEXT_NODE : false;
+            nextSibling.nodeType === nodeConstants.TEXT_NODE : false;
           let isPrevSiblingText = prevSibling ?
-            prevSibling.nodeType === Ci.nsIDOMNode.TEXT_NODE : false;
+            prevSibling.nodeType === nodeConstants.TEXT_NODE : false;
 
           // If the parent had two children and the next or previous sibling
           // is a text node, then it now has only a single text node, is about
           // to be in-lined; and focus should move to the parent.
           if (parent.numChildren === 2
               && (isNextSiblingText || isPrevSiblingText)) {
             focusNode = parent;
           }