diff --git a/common/modules/base.jsm b/common/modules/base.jsm
index e18d9434..14d36d5a 100644
--- a/common/modules/base.jsm
+++ b/common/modules/base.jsm
@@ -1742,10 +1742,10 @@ const Iter = Class("Iter", {
             "Dear sir or madam,\n" +
             "You are attempting to use this iterator object as a\n" +
             "deprecated, pre-ES6 iterator, which is known to cause\n" +
-            "major problems. Please use it in a for-of loop instead.\n" +
+            "major problems. Please use it in a for-of loop instead.\n\n" +
             "Since I don't know how far back in the call chain you\n" +
             "originate, I'm just going to give you an entire stack.\n" +
-            "Here you go:\n" + Error().stack);
+            "Here you go:\n\n" + Error().stack);
 
         throw Error("Iter object used as a pre-ES6 iterator");
     },
diff --git a/common/modules/dom.jsm b/common/modules/dom.jsm
index c240376c..d8ba6314 100644
--- a/common/modules/dom.jsm
+++ b/common/modules/dom.jsm
@@ -1486,7 +1486,7 @@ var DOM = Class("DOM", {
                         yield elem;
 
                 if (matcher.css)
-                    for (let [, elem] of iter(util.withProperErrors("querySelectorAll", node, matcher.css)))
+                    for (let elem of util.withProperErrors("querySelectorAll", node, matcher.css))
                         yield elem;
             }, {
                 css: css.join(", "),