diff --git a/.gitignore b/.gitignore
index b512c09d4..b1d62d565 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,3 @@
-node_modules
\ No newline at end of file
+node_modules
+vendor
+composer.lock
diff --git a/framework/core/src/Post/Post.php b/framework/core/src/Post/Post.php
index 8c72f6c53..8a0ba4ab5 100644
--- a/framework/core/src/Post/Post.php
+++ b/framework/core/src/Post/Post.php
@@ -96,12 +96,13 @@ class Post extends AbstractModel
 
             /** @var ConnectionInterface $db */
             $db = static::getConnectionResolver();
-            $post->number = new Expression('('.$db
-                    ->table('posts', 'pn')
+            $post->number = new Expression('('.
+                $db->table('posts', 'pn')
                     ->whereRaw($db->getTablePrefix().'pn.discussion_id = '.intval($post->discussion_id))
-                    ->select($db->raw('max('.$db->getTablePrefix().'pn.number) + 1'))
+                    // IFNULL only works on MySQL/MariaDB
+                    ->selectRaw('IFNULL(MAX('.$db->getTablePrefix().'pn.number), 0) + 1')
                     ->toSql()
-                .')');
+            .')');
         });
 
         static::created(function (self $post) {