diff --git a/packages/ember-runtime/lib/mixins/array.js b/packages/ember-runtime/lib/mixins/array.js
index 1fe9f3ae821..fcb62289990 100644
--- a/packages/ember-runtime/lib/mixins/array.js
+++ b/packages/ember-runtime/lib/mixins/array.js
@@ -141,19 +141,24 @@ export function arrayContentDidChange(array, startIdx, removeAmt, addAmt) {
 
   let meta = peekMeta(array);
   let cache = meta && meta.readableCache();
-
-  if (cache) {
-    if (cache.firstObject !== undefined &&
-        objectAt(array, 0) !== cacheFor.get(cache, 'firstObject')) {
-      propertyWillChange(array, 'firstObject', meta);
-      propertyDidChange(array, 'firstObject', meta);
-    }
-    if (cache.lastObject !== undefined &&
-        objectAt(array, get(array, 'length') - 1) !== cacheFor.get(cache, 'lastObject')) {
-      propertyWillChange(array, 'lastObject', meta);
-      propertyDidChange(array, 'lastObject', meta);
+  if (cache !== undefined) {
+    if (cache.firstObject !== undefined && startIdx === 0 && objectAt(array, 0) !== cacheFor.get(cache, 'firstObject')) {
+      propertyWillChange(array, 'firstObject');
+      propertyDidChange(array, 'firstObject');
     }
+
+    if (cache.lastObject !== undefined) {
+      let delta = (addAmt === -1 ? 0 : addAmt) - (removeAmt === -1 ? 0 : removeAmt);
+      let length = get(array, 'length');
+
+      let lastIndex = length - delta - 1;
+      if ((lastIndex === -1 || delta === 0 || !(startIdx < lastIndex && lastIndex < length)) && objectAt(array, length - 1) !== cacheFor.get(cache, 'lastObject')) {
+        propertyWillChange(array, 'lastObject');
+        propertyDidChange(array, 'lastObject');
+      }
+   }
   }
+
   return array;
 }
 
diff --git a/packages/ember-runtime/tests/suites/mutable_array/insertAt.js b/packages/ember-runtime/tests/suites/mutable_array/insertAt.js
index be4e4de840b..eb230c160b6 100644
--- a/packages/ember-runtime/tests/suites/mutable_array/insertAt.js
+++ b/packages/ember-runtime/tests/suites/mutable_array/insertAt.js
@@ -135,10 +135,20 @@ suite.test('[A,B,C].insertAt(1,X) => [A,X,B,C] + notify', function() {
   let after  = [before[0], item, before[1], before[2]];
   let obj = this.newObject(before);
   let observer = this.newObserver(obj, '[]', '@each', 'length', 'firstObject', 'lastObject');
+  let objectAtCalls = [];
+
+  let objectAt = obj.objectAt;
+  obj.objectAt = (ix) => {
+    objectAtCalls.push(ix);
+    return objectAt.call(obj, ix);
+  }
 
   obj.getProperties('firstObject', 'lastObject'); /* Prime the cache */
 
+  objectAtCalls.splice(0, objectAtCalls.length);
+
   obj.insertAt(1, item);
+  deepEqual(objectAtCalls, [], 'objectAt is not called when only inserting items');
 
   deepEqual(this.toArray(obj), after, 'post item results');
   equal(get(obj, 'length'), after.length, 'length');