diff --git a/src/Model/Contact/Group.php b/src/Model/Contact/Group.php
index 52ae70807..5a26fcaa6 100644
--- a/src/Model/Contact/Group.php
+++ b/src/Model/Contact/Group.php
@@ -79,7 +79,7 @@ class Group
 	{
 		return Contact::selectToArray([], ["`uid` = ? AND NOT `self` AND NOT `deleted` AND NOT `blocked` AND NOT `pending` AND NOT `failed`
 			AND `id` NOT IN (SELECT DISTINCT(`contact-id`) FROM `group_member` INNER JOIN `group` ON `group`.`id` = `group_member`.`gid`
-			   	WHERE `group`.`uid` = ?)", $uid, $uid]);
+			   	WHERE `group`.`uid` = ? AND `contact-id` = `contact`.`id`)", $uid, $uid]);
 	}
 
 	/**
diff --git a/src/Model/Contact/Relation.php b/src/Model/Contact/Relation.php
index b8fd3aa95..ae6859cdd 100644
--- a/src/Model/Contact/Relation.php
+++ b/src/Model/Contact/Relation.php
@@ -284,7 +284,7 @@ class Relation
 		$results = DBA::select('contact', [], ["`id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` IN
 				(SELECT `cid` FROM `contact-relation` WHERE `relation-cid` = ?)
 					AND NOT `cid` IN (SELECT `id` FROM `contact` WHERE `uid` = ? AND `nurl` IN
-						(SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` IN (?, ?))))
+						(SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` IN (?, ?))) AND `id` = `cid`)
 			AND NOT `hidden` AND `network` IN (?, ?, ?, ?)",
 			$cid,
 			0,
@@ -314,7 +314,7 @@ class Relation
 			["`id` IN (SELECT `cid` FROM `contact-relation` WHERE `relation-cid` IN
 				(SELECT `relation-cid` FROM `contact-relation` WHERE `cid` = ?)
 					AND NOT `cid` IN (SELECT `id` FROM `contact` WHERE `uid` = ? AND `nurl` IN
-						(SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` IN (?, ?))))
+						(SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` IN (?, ?))) AND `id` = `cid`)
 			AND NOT `hidden` AND `network` IN (?, ?, ?, ?)",
 			$cid, 0, $uid, Contact::FRIEND, Contact::SHARING,
 			Protocol::ACTIVITYPUB, Protocol::DFRN, $diaspora, $ostatus],
@@ -354,7 +354,7 @@ class Relation
 
 		// The query returns any contact that isn't followed by that user.
 		$results = DBA::select('contact', [],
-			["NOT `nurl` IN (SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` IN (?, ?))
+			["NOT `nurl` IN (SELECT `nurl` FROM `contact` WHERE `uid` = ? AND `rel` IN (?, ?) AND `nurl` = `nurl`)
 			AND NOT `hidden` AND `uid` = ? AND `network` IN (?, ?, ?, ?)",
 			$uid, Contact::FRIEND, Contact::SHARING, 0, 
 			Protocol::ACTIVITYPUB, Protocol::DFRN, $diaspora, $ostatus],
diff --git a/src/Model/Post.php b/src/Model/Post.php
index 31bd90012..635a84efd 100644
--- a/src/Model/Post.php
+++ b/src/Model/Post.php
@@ -400,10 +400,10 @@ class Post
 			AND ((NOT `contact-readonly` AND NOT `contact-pending` AND (`contact-rel` IN (?, ?)))
 				OR `self` OR `gravity` != ? OR `contact-uid` = ?)
 			AND NOT `" . $view . "`.`uri-id` IN (SELECT `uri-id` FROM `post-user` WHERE `uid` = ? AND `hidden`)
-			AND NOT `author-id` IN (SELECT `cid` FROM `user-contact` WHERE `uid` = ? AND `blocked`)
-			AND NOT `owner-id` IN (SELECT `cid` FROM `user-contact` WHERE `uid` = ? AND `blocked`)
-			AND NOT (`gravity` = ? AND `author-id` IN (SELECT `cid` FROM `user-contact` WHERE `uid` = ? AND `ignored`))
-			AND NOT (`gravity` = ? AND `owner-id` IN (SELECT `cid` FROM `user-contact` WHERE `uid` = ? AND `ignored`))",
+			AND NOT `author-id` IN (SELECT `cid` FROM `user-contact` WHERE `uid` = ? AND `blocked` AND `cid` = `author-id`)
+			AND NOT `owner-id` IN (SELECT `cid` FROM `user-contact` WHERE `uid` = ? AND `blocked` AND `cid` = `owner-id`)
+			AND NOT (`gravity` = ? AND `author-id` IN (SELECT `cid` FROM `user-contact` WHERE `uid` = ? AND `ignored` AND `cid` = `author-id`))
+			AND NOT (`gravity` = ? AND `owner-id` IN (SELECT `cid` FROM `user-contact` WHERE `uid` = ? AND `ignored` AND `cid` = `owner-id`))",
 				0, Contact::SHARING, Contact::FRIEND, Item::GRAVITY_PARENT, 0, $uid, $uid, $uid, Item::GRAVITY_PARENT, $uid, Item::GRAVITY_PARENT, $uid]);
 
 		$select_string = implode(', ', array_map([DBA::class, 'quoteIdentifier'], $selected));
diff --git a/src/Module/Api/Mastodon/Timelines/Home.php b/src/Module/Api/Mastodon/Timelines/Home.php
index 3a18baecb..f3cbd8d5b 100644
--- a/src/Module/Api/Mastodon/Timelines/Home.php
+++ b/src/Module/Api/Mastodon/Timelines/Home.php
@@ -82,7 +82,7 @@ class Home extends BaseApi
 		}
 
 		if ($request['remote']) {
-			$condition = DBA::mergeConditions($condition, ["NOT `uri-id` IN (SELECT `uri-id` FROM `post-user` WHERE `origin`)"]);
+			$condition = DBA::mergeConditions($condition, ["NOT `uri-id` IN (SELECT `uri-id` FROM `post-user` WHERE `origin` AND `post-user`.`uri-id` = `post-user-view`.`uri-id`)"]);
 		}
 
 		if ($request['exclude_replies']) {
diff --git a/src/Module/Api/Mastodon/Timelines/ListTimeline.php b/src/Module/Api/Mastodon/Timelines/ListTimeline.php
index c786e3d9d..df6fdb39d 100644
--- a/src/Module/Api/Mastodon/Timelines/ListTimeline.php
+++ b/src/Module/Api/Mastodon/Timelines/ListTimeline.php
@@ -91,7 +91,7 @@ class ListTimeline extends BaseApi
 		}
 
 		if ($request['remote']) {
-			$condition = DBA::mergeConditions($condition, ["NOT `uri-id` IN (SELECT `uri-id` FROM `post-user` WHERE `origin`)"]);
+			$condition = DBA::mergeConditions($condition, ["NOT `uri-id` IN (SELECT `uri-id` FROM `post-user` WHERE `origin` AND `post-user`.`uri-id` = `post-user-view`.`uri-id`)"]);
 		}
 
 		$items = Post::selectForUser($uid, ['uri-id'], $condition, $params);
diff --git a/src/Module/Api/Mastodon/Timelines/PublicTimeline.php b/src/Module/Api/Mastodon/Timelines/PublicTimeline.php
index cc2392caf..066c4b83f 100644
--- a/src/Module/Api/Mastodon/Timelines/PublicTimeline.php
+++ b/src/Module/Api/Mastodon/Timelines/PublicTimeline.php
@@ -65,7 +65,7 @@ class PublicTimeline extends BaseApi
 		}
 
 		if ($request['remote']) {
-			$condition = DBA::mergeConditions($condition, ["NOT `uri-id` IN (SELECT `uri-id` FROM `post-user` WHERE `origin`)"]);
+			$condition = DBA::mergeConditions($condition, ["NOT `uri-id` IN (SELECT `uri-id` FROM `post-user` WHERE `origin` AND `post-user`.`uri-id` = `post-view`.`uri-id`)"]);
 		}
 
 		if ($request['only_media']) {
@@ -92,7 +92,7 @@ class PublicTimeline extends BaseApi
 
 		if (!empty($uid)) {
 			$condition = DBA::mergeConditions($condition,
-				["NOT `parent-author-id` IN (SELECT `cid` FROM `user-contact` WHERE `uid` = ? AND (`blocked` OR `ignored`))", $uid]);
+				["NOT `parent-author-id` IN (SELECT `cid` FROM `user-contact` WHERE `uid` = ? AND (`blocked` OR `ignored`) AND `cid` = `parent-author-id`)", $uid]);
 		}
 
 		$items = Post::selectPostsForUser($uid, ['uri-id'], $condition, $params);
diff --git a/src/Module/Api/Mastodon/Timelines/Tag.php b/src/Module/Api/Mastodon/Timelines/Tag.php
index bc4464b56..2049d9207 100644
--- a/src/Module/Api/Mastodon/Timelines/Tag.php
+++ b/src/Module/Api/Mastodon/Timelines/Tag.php
@@ -77,7 +77,7 @@ class Tag extends BaseApi
 		}
 
 		if ($request['remote']) {
-			$condition = DBA::mergeConditions($condition, ["NOT `uri-id` IN (SELECT `uri-id` FROM `post-user` WHERE `origin`)"]);
+			$condition = DBA::mergeConditions($condition, ["NOT `uri-id` IN (SELECT `uri-id` FROM `post-user` WHERE `origin` AND `post-user`.`uri-id` = `tag-search-view`.`uri-id`)"]);
 		}
 
 		if ($request['only_media']) {
diff --git a/src/Module/Conversation/Community.php b/src/Module/Conversation/Community.php
index b2cbf1014..7e6730f83 100644
--- a/src/Module/Conversation/Community.php
+++ b/src/Module/Conversation/Community.php
@@ -335,7 +335,7 @@ class Community extends BaseModule
 			$condition[] = $item_id;
 		} else {
 			if (DI::userSession()->getLocalUserId() && !empty($_REQUEST['no_sharer'])) {
-				$condition[0] .= " AND NOT `uri-id` IN (SELECT `uri-id` FROM `post-user` WHERE `post-user`.`uid` = ?)";
+				$condition[0] .= " AND NOT `uri-id` IN (SELECT `uri-id` FROM `post-user` WHERE `post-user`.`uid` = ? AND `post-user`.`uri-id` = `post-thread-user-view`.`uri-id`)";
 				$condition[] = DI::userSession()->getLocalUserId();
 			}
 	
diff --git a/src/Protocol/Diaspora.php b/src/Protocol/Diaspora.php
index ffffaf619..8a5969dde 100644
--- a/src/Protocol/Diaspora.php
+++ b/src/Protocol/Diaspora.php
@@ -54,7 +54,8 @@ use GuzzleHttp\Psr7\Uri;
 use SimpleXMLElement;
 
 /**
- * This class contain functions to create and send Diaspora XML files
+ * This class contains functions to communicate via the Diaspora protocol
+ * @see https://diaspora.github.io/diaspora_federation/
  */
 class Diaspora
 {
diff --git a/src/Worker/RemoveUnusedAvatars.php b/src/Worker/RemoveUnusedAvatars.php
index 4591fb22b..27a6ac676 100644
--- a/src/Worker/RemoveUnusedAvatars.php
+++ b/src/Worker/RemoveUnusedAvatars.php
@@ -37,11 +37,11 @@ class RemoveUnusedAvatars
 		$sql = "FROM `contact` INNER JOIN `photo` ON `contact`.`id` = `contact-id`
 			WHERE `contact`.`uid` = ? AND NOT `self` AND (`photo` != ? OR `thumb` != ? OR `micro` != ?)
 				AND NOT `nurl` IN (SELECT `nurl` FROM `contact` WHERE `uid` != ?)
-				AND NOT `contact`.`id` IN (SELECT `author-id` FROM `post-user`)
-				AND NOT `contact`.`id` IN (SELECT `owner-id` FROM `post-user`)
-				AND NOT `contact`.`id` IN (SELECT `causer-id` FROM `post-user` WHERE `causer-id` IS NOT NULL)
-				AND NOT `contact`.`id` IN (SELECT `cid` FROM `post-tag`)
-				AND NOT `contact`.`id` IN (SELECT `contact-id` FROM `post-user`);";
+				AND NOT `contact`.`id` IN (SELECT `author-id` FROM `post-user` WHERE `author-id` = `contact`.`id`)
+				AND NOT `contact`.`id` IN (SELECT `owner-id` FROM `post-user` WHERE `owner-id` = `contact`.`id`)
+				AND NOT `contact`.`id` IN (SELECT `causer-id` FROM `post-user` WHERE `causer-id` IS NOT NULL AND `causer-id` = `contact`.`id`)
+				AND NOT `contact`.`id` IN (SELECT `cid` FROM `post-tag` WHERE `cid` = `contact`.`id`)
+				AND NOT `contact`.`id` IN (SELECT `contact-id` FROM `post-user` WHERE `contact-id` = `contact`.`id`);";
 
 		$ret = DBA::fetchFirst("SELECT COUNT(*) AS `total` " . $sql, 0, '', '', '', 0);
 		$total = $ret['total'] ?? 0;
diff --git a/src/Worker/RemoveUnusedContacts.php b/src/Worker/RemoveUnusedContacts.php
index 038376c22..1cbb3775c 100644
--- a/src/Worker/RemoveUnusedContacts.php
+++ b/src/Worker/RemoveUnusedContacts.php
@@ -39,10 +39,14 @@ class RemoveUnusedContacts
 	{
 		$condition = ["`id` != ? AND `uid` = ? AND NOT `self` AND NOT `nurl` IN (SELECT `nurl` FROM `contact` WHERE `uid` != ?)
 			AND (NOT `network` IN (?, ?, ?, ?, ?, ?) OR (`archive` AND `success_update` < ?))
-			AND NOT `id` IN (SELECT `author-id` FROM `post-user`) AND NOT `id` IN (SELECT `owner-id` FROM `post-user`)
-			AND NOT `id` IN (SELECT `causer-id` FROM `post-user` WHERE `causer-id` IS NOT NULL) AND NOT `id` IN (SELECT `cid` FROM `post-tag`)
-			AND NOT `id` IN (SELECT `contact-id` FROM `post-user`) AND NOT `id` IN (SELECT `cid` FROM `user-contact`)
-			AND NOT `id` IN (SELECT `cid` FROM `event`) AND NOT `id` IN (SELECT `contact-id` FROM `group_member`)
+			AND NOT `id` IN (SELECT `author-id` FROM `post-user` WHERE `author-id` = `contact`.`id`)
+			AND NOT `id` IN (SELECT `owner-id` FROM `post-user` WHERE `owner-id` = `contact`.`id`)
+			AND NOT `id` IN (SELECT `causer-id` FROM `post-user` WHERE `causer-id` IS NOT NULL AND `causer-id` = `contact`.`id`)
+			AND NOT `id` IN (SELECT `cid` FROM `post-tag` WHERE `cid` = `contact`.`id`)
+			AND NOT `id` IN (SELECT `contact-id` FROM `post-user` WHERE `contact-id` = `contact`.`id`)
+			AND NOT `id` IN (SELECT `cid` FROM `user-contact` WHERE `cid` = `contact`.`id`)
+			AND NOT `id` IN (SELECT `cid` FROM `event` WHERE `cid` = `contact`.`id`)
+			AND NOT `id` IN (SELECT `contact-id` FROM `group_member` WHERE `contact-id` = `contact`.`id`)
 			AND `created` < ?",
 			0, 0, 0, Protocol::DFRN, Protocol::DIASPORA, Protocol::OSTATUS, Protocol::FEED, Protocol::MAIL, Protocol::ACTIVITYPUB, DateTimeFormat::utc('now - 365 days'), DateTimeFormat::utc('now - 30 days')];
 
diff --git a/src/Worker/RemoveUnusedTags.php b/src/Worker/RemoveUnusedTags.php
index 90ebd673f..ecb724c38 100644
--- a/src/Worker/RemoveUnusedTags.php
+++ b/src/Worker/RemoveUnusedTags.php
@@ -30,6 +30,6 @@ class RemoveUnusedTags
 	 */
 	public static function execute()
 	{
-		DBA::delete('tag', ["NOT `id` IN (SELECT `tid` FROM `post-category`) AND NOT `id` IN (SELECT `tid` FROM `post-tag`)"]);
+		DBA::delete('tag', ["NOT `id` IN (SELECT `tid` FROM `post-category` WHERE `tid` = `tag`.`id`) AND NOT `id` IN (SELECT `tid` FROM `post-tag` WHERE `tid` = `tag`.`id`)"]);
 	}
 }