diff --git a/src/Illuminate/Support/Collection.php b/src/Illuminate/Support/Collection.php
index d89737e62d22..387b35b453e4 100644
--- a/src/Illuminate/Support/Collection.php
+++ b/src/Illuminate/Support/Collection.php
@@ -122,8 +122,16 @@ public function all()
      */
     public function avg($callback = null)
     {
-        if ($count = $this->count()) {
-            return $this->sum($callback) / $count;
+        $callback = $this->valueRetriever($callback);
+
+        $items = $this->map(function ($value) use ($callback) {
+            return $callback($value);
+        })->filter(function ($value) {
+            return ! is_null($value);
+        });
+
+        if ($count = $items->count()) {
+            return $items->sum() / $count;
         }
     }
 
diff --git a/tests/Support/SupportCollectionTest.php b/tests/Support/SupportCollectionTest.php
index 3601dca9c062..e503a3de0be7 100755
--- a/tests/Support/SupportCollectionTest.php
+++ b/tests/Support/SupportCollectionTest.php
@@ -2098,6 +2098,13 @@ public function testGettingAvgItemsFromCollection()
         $this->assertEquals(15, $c->avg('foo'));
         $this->assertEquals(15, $c->avg->foo);
 
+        $c = new Collection([(object) ['foo' => 10], (object) ['foo' => 20], (object) ['foo' => null]]);
+        $this->assertEquals(15, $c->avg(function ($item) {
+            return $item->foo;
+        }));
+        $this->assertEquals(15, $c->avg('foo'));
+        $this->assertEquals(15, $c->avg->foo);
+
         $c = new Collection([['foo' => 10], ['foo' => 20]]);
         $this->assertEquals(15, $c->avg('foo'));
         $this->assertEquals(15, $c->avg->foo);