--- a/toolkit/content/preferencesBindings.js
+++ b/toolkit/content/preferencesBindings.js
@@ -360,18 +360,19 @@ const Preferences = window.Preferences =
       function setValue(element, attribute, value) {
         if (attribute in element) {
           element[attribute] = value;
         } else if (attribute === "checked") {
           // The "checked" attribute can't simply be set to the specified value;
           // it has to be set if the value is true and removed if the value
           // is false in order to be interpreted correctly by the element.
           if (value) {
-            // We can set it to anything; convention is to set it to itself.
-            element.setAttribute(attribute, attribute);
+            // In theory we can set it to anything; however xbl implementations
+            // of `checkbox` and `listitem` only work with "true".
+            element.setAttribute(attribute, "true");
           } else {
             element.removeAttribute(attribute);
           }
         } else {
           element.setAttribute(attribute, value);
         }
       }
       if (aElement.localName == "checkbox" ||