--- a/browser/modules/ExtensionsUI.jsm
+++ b/browser/modules/ExtensionsUI.jsm
@@ -258,19 +258,19 @@ this.ExtensionsUI = {
       popupIconURL: info.icon,
       persistent: true,
 
       eventCallback(topic) {
         if (topic == "showing") {
           let doc = this.browser.ownerDocument;
           doc.getElementById("addon-webext-perm-header").innerHTML = header;
 
-          if (text) {
-            doc.getElementById("addon-webext-perm-text").innerHTML = text;
-          }
+          let textEl = doc.getElementById("addon-webext-perm-text");
+          textEl.innerHTML = text;
+          textEl.hidden = !text;
 
           let listIntroEl = doc.getElementById("addon-webext-perm-intro");
           listIntroEl.value = listIntro;
           listIntroEl.hidden = (msgs.length == 0);
 
           let list = doc.getElementById("addon-webext-perm-list");
           while (list.firstChild) {
             list.firstChild.remove();