diff --git a/lib/Collection.php b/lib/Collection.php
index 9763d4ac..d50e26be 100644
--- a/lib/Collection.php
+++ b/lib/Collection.php
@@ -104,10 +104,10 @@ class Collection{
 	 */
 	public static function DeleteUnused(): void{
 		Db::Query('
-			DELETE
-			from Collections
-			where CollectionId not in
-				(select distinct CollectionId from CollectionEbooks)
+			DELETE c
+			from Collections c
+				left join CollectionEbooks ce using (CollectionId)
+			where ce.CollectionId is null
 		');
 	}
 
diff --git a/lib/EbookTag.php b/lib/EbookTag.php
index bfa6fcaf..138a3184 100644
--- a/lib/EbookTag.php
+++ b/lib/EbookTag.php
@@ -113,11 +113,11 @@ class EbookTag extends Tag{
 	 */
 	public static function DeleteUnused(): void{
 		Db::Query('
-			DELETE
-			from Tags
-			where Type = ?
-				and TagId not in
-					(select distinct TagId from EbookTags)
+			DELETE t
+			from Tags t 
+				left join EbookTags et using (TagId)
+			where t.Type = ?
+				and et.TagId is null
 		', [Enums\TagType::Ebook]);
 	}
 }
diff --git a/lib/LocSubject.php b/lib/LocSubject.php
index 880fb3a1..36d4bf07 100644
--- a/lib/LocSubject.php
+++ b/lib/LocSubject.php
@@ -70,10 +70,10 @@ class LocSubject{
 	 */
 	public static function DeleteUnused(): void{
 		Db::Query('
-			DELETE
-			from LocSubjects
-			where LocSubjectId not in
-				(select distinct LocSubjectId from EbookLocSubjects)
+			DELETE ls
+			from LocSubjects ls
+				left join EbookLocSubjects els using (LocSubjectId)
+			where els.LocSubjectId is null
 		');
 	}
 }