diff --git a/pracman/practice/migrations/0001_initial.py b/pracman/practice/migrations/0001_initial.py
index ced83ce..11dde15 100644
--- a/pracman/practice/migrations/0001_initial.py
+++ b/pracman/practice/migrations/0001_initial.py
@@ -1,6 +1,4 @@
-# -*- coding: utf-8 -*-
-# Generated by Django 1.11.5 on 2017-09-22 00:02
-from __future__ import unicode_literals
+# Generated by Django 2.1.7 on 2019-03-05 12:39
 
 from django.conf import settings
 import django.contrib.auth.models
@@ -15,7 +13,7 @@ class Migration(migrations.Migration):
     initial = True
 
     dependencies = [
-        ('auth', '0008_alter_user_username_max_length'),
+        ('auth', '0009_alter_user_last_name_max_length'),
     ]
 
     operations = [
@@ -28,7 +26,7 @@ class Migration(migrations.Migration):
                 ('is_superuser', models.BooleanField(default=False, help_text='Designates that this user has all permissions without explicitly assigning them.', verbose_name='superuser status')),
                 ('username', models.CharField(error_messages={'unique': 'A user with that username already exists.'}, help_text='Required. 150 characters or fewer. Letters, digits and @/./+/-/_ only.', max_length=150, unique=True, validators=[django.contrib.auth.validators.UnicodeUsernameValidator()], verbose_name='username')),
                 ('first_name', models.CharField(blank=True, max_length=30, verbose_name='first name')),
-                ('last_name', models.CharField(blank=True, max_length=30, verbose_name='last name')),
+                ('last_name', models.CharField(blank=True, max_length=150, verbose_name='last name')),
                 ('email', models.EmailField(blank=True, max_length=254, verbose_name='email address')),
                 ('is_staff', models.BooleanField(default=False, help_text='Designates whether the user can log into this admin site.', verbose_name='staff status')),
                 ('is_active', models.BooleanField(default=True, help_text='Designates whether this user should be treated as active. Unselect this instead of deleting accounts.', verbose_name='active')),
@@ -48,7 +46,7 @@ class Migration(migrations.Migration):
                 ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                 ('at', models.DateTimeField()),
                 ('created_at', models.DateTimeField(auto_now_add=True)),
-                ('doctor', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL)),
+                ('doctor', models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, to=settings.AUTH_USER_MODEL)),
             ],
             options={
                 'ordering': ('-at',),
@@ -74,17 +72,17 @@ class Migration(migrations.Migration):
         migrations.AddField(
             model_name='patient',
             name='practice',
-            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='practice.Practice'),
+            field=models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, to='practice.Practice'),
         ),
         migrations.AddField(
             model_name='appointment',
             name='patient',
-            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='practice.Patient'),
+            field=models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, to='practice.Patient'),
         ),
         migrations.AddField(
             model_name='doctor',
             name='practice',
-            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, related_name='doctors', to='practice.Practice'),
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.PROTECT, related_name='doctors', to='practice.Practice'),
         ),
         migrations.AddField(
             model_name='doctor',
@@ -93,6 +91,6 @@ class Migration(migrations.Migration):
         ),
         migrations.AlterUniqueTogether(
             name='appointment',
-            unique_together=set([('doctor', 'at')]),
+            unique_together={('doctor', 'at')},
         ),
     ]
diff --git a/pracman/practice/models.py b/pracman/practice/models.py
index 9b8b628..bf1a5f1 100644
--- a/pracman/practice/models.py
+++ b/pracman/practice/models.py
@@ -15,7 +15,7 @@ def __str__(self):
 
 class Doctor(AbstractUser):
 
-    practice = models.ForeignKey('practice.Practice', null=True, blank=True, related_name='doctors')
+    practice = models.ForeignKey('practice.Practice', null=True, blank=True, related_name='doctors', on_delete=models.PROTECT)
 
     class Meta:
         verbose_name_plural = 'Doctors'
@@ -24,7 +24,7 @@ class Meta:
 class Patient(models.Model):
 
     name = models.CharField(max_length=128)
-    practice = models.ForeignKey('practice.Practice')
+    practice = models.ForeignKey('practice.Practice', on_delete=models.PROTECT)
     create_at = models.DateTimeField(auto_now_add=True)
 
     objects = querysets.PatientQuerySet.as_manager()
@@ -35,8 +35,8 @@ def __str__(self):
 
 class Appointment(models.Model):
 
-    doctor = models.ForeignKey('practice.Doctor')
-    patient = models.ForeignKey('practice.Patient')
+    doctor = models.ForeignKey('practice.Doctor', on_delete=models.PROTECT)
+    patient = models.ForeignKey('practice.Patient', on_delete=models.PROTECT)
     at = models.DateTimeField()
     created_at = models.DateTimeField(auto_now_add=True)
 
diff --git a/requirements.txt b/requirements.txt
index 3e0a788..2f19d37 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,2 @@
-Django==1.11.5
-djangorestframework==3.6.4
+Django==2.1.7
+djangorestframework==3.9.1