diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index dfba1179a3..b952e4d07d 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -271,6 +271,7 @@ p a {
 		<li>[Fix] Do not erase ranks and avatars when changing default groups (Bugs #13701, #13697)</li>
 		<li>[Fix] Limit author searches to firstpost, if selected (Bug #13579)</li>
 		<li>[Fix] store Date custom profile field defaults on multi-lingual boards </li>
+		<li>[Fix] Properly resync user post counts for users that have no posts (Bug #13581)</li>
 	</ul>
 
 	</div>
diff --git a/phpBB/includes/acp/acp_main.php b/phpBB/includes/acp/acp_main.php
index b43ca5f9dd..770c82552f 100644
--- a/phpBB/includes/acp/acp_main.php
+++ b/phpBB/includes/acp/acp_main.php
@@ -161,15 +161,15 @@ class acp_main
 							trigger_error($user->lang['NO_AUTH_OPERATION'] . adm_back_link($this->u_action), E_USER_WARNING);
 						}
 
-						$sql = 'SELECT COUNT(post_id) AS num_posts, poster_id
-							FROM ' . POSTS_TABLE . '
-							WHERE post_postcount = 1
-							GROUP BY poster_id';
+						$sql = 'SELECT COUNT(p.post_id) AS num_posts, u.user_id
+							FROM ' . USERS_TABLE . ' u
+							LEFT JOIN  ' . POSTS_TABLE . ' p ON (u.user_id = p.poster_id AND p.post_postcount = 1)
+							GROUP BY u.user_id';
 						$result = $db->sql_query($sql);
 
 						while ($row = $db->sql_fetchrow($result))
 						{
-							$db->sql_query('UPDATE ' . USERS_TABLE . " SET user_posts = {$row['num_posts']} WHERE user_id = {$row['poster_id']}");
+							$db->sql_query('UPDATE ' . USERS_TABLE . " SET user_posts = {$row['num_posts']} WHERE user_id = {$row['user_id']}");
 						}
 						$db->sql_freeresult($result);