--- a/devtools/client/styleeditor/StyleEditorUI.jsm
+++ b/devtools/client/styleeditor/StyleEditorUI.jsm
@@ -894,17 +894,17 @@ StyleEditorUI.prototype = {
         div.addEventListener("click",
                              this._jumpToLocation.bind(this, location));
 
         let cond = this._panelDoc.createElement("div");
         cond.className = "media-rule-condition";
         if (!rule.matches) {
           cond.classList.add("media-condition-unmatched");
         }
-        if (this._target.tab.tagName == "tab") {
+        if (this._target.isLocalTab) {
           this._setConditionContents(cond, rule.conditionText);
         } else {
           cond.textContent = rule.conditionText;
         }
         div.appendChild(cond);
 
         let link = this._panelDoc.createElement("div");
         link.className = "media-rule-line theme-link";