diff --git a/docker_challenges/__init__.py b/docker_challenges/__init__.py
index 4fcace0..190ef35 100644
--- a/docker_challenges/__init__.py
+++ b/docker_challenges/__init__.py
@@ -403,9 +403,9 @@ def delete(challenge):
             delete_file(f.id)
         ChallengeFiles.query.filter_by(challenge_id=challenge.id).delete()
         Tags.query.filter_by(challenge_id=challenge.id).delete()
-        Hints.query.filter_by(challenge_id=challenge.id).delete()        
+        Hints.query.filter_by(challenge_id=challenge.id).delete()
         DockerChallenge.query.filter_by(id=challenge.id).delete()
-	Challenges.query.filter_by(id=challenge.id).delete()
+        Challenges.query.filter_by(id=challenge.id).delete()
         db.session.commit()
 
     @staticmethod