diff --git a/src/Flarum/Api/Actions/Posts/Create.php b/src/Flarum/Api/Actions/Posts/Create.php
index c6864b048..f1c3943be 100644
--- a/src/Flarum/Api/Actions/Posts/Create.php
+++ b/src/Flarum/Api/Actions/Posts/Create.php
@@ -20,7 +20,7 @@ class Create extends Base
         // the post content, and the author's user account. Let's set up a
         // command with this information. We also fire an event to allow plugins
         // to add data to the command.
-        $discussionId = $this->input('posts.links.discussions');
+        $discussionId = $this->input('posts.links.discussion');
         $content = $this->input('posts.content');
         $command = new PostReplyCommand($discussionId, $content, User::current());
 
diff --git a/src/Flarum/Core/Posts/CommentPost.php b/src/Flarum/Core/Posts/CommentPost.php
index 01f178162..32999f863 100755
--- a/src/Flarum/Core/Posts/CommentPost.php
+++ b/src/Flarum/Core/Posts/CommentPost.php
@@ -15,7 +15,7 @@ class CommentPost extends Post
         parent::boot();
 
         static::saving(function ($post) {
-            $post->number = $post->discussion->number_index++;
+            $post->number = ++$post->discussion->number_index;
             $post->discussion->save();
         });
     }