--- a/devtools/client/inspector/markup/views/element-container.js
+++ b/devtools/client/inspector/markup/views/element-container.js
@@ -41,17 +41,17 @@ function MarkupElementContainer(markupVi
     throw new Error("Invalid node for MarkupElementContainer");
   }
 
   this.tagLine.appendChild(this.editor.elt);
 }
 
 MarkupElementContainer.prototype = extend(MarkupContainer.prototype, {
   _buildEventTooltipContent: Task.async(function* (target, tooltip) {
-    if (target.hasAttribute("data-event")) {
+    if (target.dataset.event) {
       yield tooltip.hide();
 
       let listenerInfo = yield this.node.getEventListenerInfo();
 
       let toolbox = this.markup.toolbox;
 
       setEventTooltip(tooltip, listenerInfo, toolbox);
       // Disable the image preview tooltip while we display the event details