diff --git a/models.py b/models.py
index 42d083a..07d728f 100644
--- a/models.py
+++ b/models.py
@@ -149,8 +149,8 @@ class UserContainer(db.Model):
     blocked_by = db.Column(db.Integer, db.ForeignKey('user.id', ondelete='SET NULL'), nullable=True)
 
     # Relationships
-    user = db.relationship('User', foreign_keys=[user_id], back_populates='containers')
-    blocker = db.relationship('User', foreign_keys=[blocked_by])
+    user = db.relationship('User', foreign_keys=['user_id'], back_populates='containers')
+    blocker = db.relationship('User', foreign_keys=['blocked_by'])
 
     # Unique: Ein User kann nur einen Container pro Typ haben
     __table_args__ = (