diff --git a/ki/models.py b/ki/models.py
index 1cac430..f9a6c20 100644
--- a/ki/models.py
+++ b/ki/models.py
@@ -29,7 +29,7 @@ class Token(db.Model):
     __tablename__ = "token"
 
     id = Column(Integer, primary_key=True)
-    user_id = Column(Integer, ForeignKey("user.id"))
+    user_id = Column(Integer, ForeignKey("user.id"), nullable=False)
     token = Column(String(36), nullable=False)
 
     user = relationship("User", back_populates="tokens")
@@ -39,9 +39,9 @@ class Contact(db.Model):
     __tablename__ = "contact"
 
     id = Column(Integer, primary_key=True)
-    user_id = Column(Integer, ForeignKey("user.id"))
+    user_id = Column(Integer, ForeignKey("user.id"), nullable=False)
     user = relationship("User", back_populates="contacts")
-    contacttype_id = Column(Integer, ForeignKey("contacttype.id"))
+    contacttype_id = Column(Integer, ForeignKey("contacttype.id"), nullable=False)
     contacttype = relationship("ContactType")
     content = Column(String(200), nullable=False)
 
@@ -65,7 +65,7 @@ class Address(db.Model):
     city = Column(String(25), default="")
     country = Column(String(25), default="")
 
-    user_id = Column(Integer, ForeignKey("user.id"))
+    user_id = Column(Integer, ForeignKey("user.id"), nullable=False)
     user = relationship("User", back_populates="address")