diff --git a/lib/Github/Api/PullRequest/Review.php b/lib/Github/Api/PullRequest/Review.php
index 40c8db83127..83182ad3c76 100644
--- a/lib/Github/Api/PullRequest/Review.php
+++ b/lib/Github/Api/PullRequest/Review.php
@@ -159,11 +159,22 @@ public function submit($username, $repository, $pullRequest, $id, array $params
      * @param string $repository  the repository
      * @param int    $pullRequest the pull request number
      * @param int    $id          the review id
+     * @param string  $message    a mandatory dismissal message
      *
      * @return array|string
      */
-    public function dismiss($username, $repository, $pullRequest, $id)
+    public function dismiss($username, $repository, $pullRequest, $id, $message)
     {
-        return $this->put('/repos/'.rawurlencode($username).'/'.rawurlencode($repository).'/pulls/'.$pullRequest.'/reviews/'.$id.'/dismissals');
+        if (!is_string($message)) {
+            throw new InvalidArgumentException(sprintf('"message" must be a valid string ("%s" given).', gettype($message)));
+        }
+
+        if (empty($message)) {
+            throw new InvalidArgumentException('"message" is mandatory and cannot be empty');
+        }
+
+        return $this->put('/repos/'.rawurlencode($username).'/'.rawurlencode($repository).'/pulls/'.$pullRequest.'/reviews/'.$id.'/dismissals', [
+          'message' => $message
+        ]);
     }
 }
diff --git a/test/Github/Tests/Api/PullRequest/ReviewTest.php b/test/Github/Tests/Api/PullRequest/ReviewTest.php
index 54b8d55aafe..441240ecfd3 100644
--- a/test/Github/Tests/Api/PullRequest/ReviewTest.php
+++ b/test/Github/Tests/Api/PullRequest/ReviewTest.php
@@ -391,7 +391,7 @@ public function shouldDismissReview()
             ->with('/repos/octocat/Hello-World/pulls/12/reviews/80/dismissals')
             ->willReturn($expectedValue);
 
-        $this->assertSame($expectedValue, $api->dismiss('octocat', 'Hello-World', 12, 80));
+        $this->assertSame($expectedValue, $api->dismiss('octocat', 'Hello-World', 12, 80, 'Dismiss reason'));
     }
 
     protected function getApiClass()