diff --git a/packages/ember-glimmer/lib/renderer.js b/packages/ember-glimmer/lib/renderer.js
index 2c17e8a3b0c..e598f0d96e8 100644
--- a/packages/ember-glimmer/lib/renderer.js
+++ b/packages/ember-glimmer/lib/renderer.js
@@ -70,9 +70,7 @@ class RootState {
       let result = this.result = iteratorResult.value;
 
       // override .render function after initial render
-      this.render = () => {
-        result.rerender(options);
-      };
+      this.render = () => result.rerender(options);
     };
   }
 
diff --git a/packages/ember-runtime/lib/computed/reduce_computed_macros.js b/packages/ember-runtime/lib/computed/reduce_computed_macros.js
index 5745c10ff7d..13b81512664 100644
--- a/packages/ember-runtime/lib/computed/reduce_computed_macros.js
+++ b/packages/ember-runtime/lib/computed/reduce_computed_macros.js
@@ -4,14 +4,13 @@
 */
 
 import { guidFor } from 'ember-utils';
-import { assert, Error as EmberError } from 'ember-debug';
+import { assert } from 'ember-debug';
 import {
   get,
   ComputedProperty,
   computed,
   addObserver,
   removeObserver,
-  isNone,
   getProperties,
   WeakMap
 } from 'ember-metal';
@@ -573,9 +572,9 @@ export function intersect(...args) {
   @public
 */
 export function setDiff(setAProperty, setBProperty) {
-  if (arguments.length !== 2) {
-    throw new EmberError('setDiff requires exactly two dependent arrays.');
-  }
+  assert('Ember.computed.setDiff requires exactly two dependent arrays.',
+    arguments.length === 2
+  );
 
   return computed(`${setAProperty}.[]`, `${setBProperty}.[]`, function() {
     let setA = this.get(setAProperty);
@@ -620,7 +619,7 @@ export function collect(...dependentKeys) {
     let res = emberA();
     for (let key in properties) {
       if (properties.hasOwnProperty(key)) {
-        if (isNone(properties[key])) {
+        if (properties[key] === undefined) {
           res.push(null);
         } else {
           res.push(properties[key]);
diff --git a/packages/ember-runtime/tests/computed/reduce_computed_macros_test.js b/packages/ember-runtime/tests/computed/reduce_computed_macros_test.js
index bdf336810f6..7c13a55d879 100644
--- a/packages/ember-runtime/tests/computed/reduce_computed_macros_test.js
+++ b/packages/ember-runtime/tests/computed/reduce_computed_macros_test.js
@@ -639,17 +639,17 @@ QUnit.test('setDiff is readOnly', function() {
   }, /Cannot set read-only property "diff" on object:/);
 });
 
-QUnit.test('it throws an error if given fewer or more than two dependent properties', function() {
-  throws(function () {
+QUnit.test('it asserts if given fewer or more than two dependent properties', function() {
+  expectAssertion(function () {
     EmberObject.extend({
       diff: setDiff('array')
     }).create({
       array: emberA([1, 2, 3, 4, 5, 6, 7]),
       array2: emberA([3, 4, 5])
     });
-  }, /requires exactly two dependent arrays/, 'setDiff requires two dependent arrays');
+  }, /Ember\.computed\.setDiff requires exactly two dependent arrays/, 'setDiff requires two dependent arrays');
 
-  throws(function () {
+  expectAssertion(function () {
     EmberObject.extend({
       diff: setDiff('array', 'array2', 'array3')
     }).create({
@@ -657,7 +657,7 @@ QUnit.test('it throws an error if given fewer or more than two dependent propert
       array2: emberA([3, 4, 5]),
       array3: emberA([7])
     });
-  }, /requires exactly two dependent arrays/, 'setDiff requires two dependent arrays');
+  }, /Ember\.computed\.setDiff requires exactly two dependent arrays/, 'setDiff requires two dependent arrays');
 });