diff --git a/api/models/vak.py b/api/models/vak.py
index 47b56752..d9891c1b 100644
--- a/api/models/vak.py
+++ b/api/models/vak.py
@@ -1,5 +1,7 @@
 from django.db import models
-from django.core.exceptions import ValidationError
+from django.db.models.signals import m2m_changed
+from django.dispatch import receiver
+from api.models.gebruiker import Gebruiker
 
 
 class Vak(models.Model):
@@ -12,11 +14,15 @@ class Vak(models.Model):
     def __str__(self):
         return self.name
     
-    def save(self, *args, **kwargs):
-        if self.teachers.filter(is_lesgever=False).exists():
-            raise ValidationError("Niet alle gebruikers in 'teachers' zijn lesgevers.")
 
-        if self.students.filter(is_lesgever=True).exists():
-            raise ValidationError("Niet alle gebruikers in 'students' zijn studenten.")
-
-        super(Vak, self).save(*args, **kwargs)
+@receiver(m2m_changed, sender=Vak.students.through)
+@receiver(m2m_changed, sender=Vak.teachers.through)
+def update_gebruiker_subjects(sender, instance, action, **kwargs):
+    if action == 'post_add':
+        for gebruiker_id in kwargs['pk_set']:
+            gebruiker = Gebruiker.objects.get(pk=gebruiker_id)
+            gebruiker.subjects.add(instance)
+    if action == 'post_remove':
+        for gebruiker_id in kwargs['pk_set']:
+            gebruiker = Gebruiker.objects.get(pk=gebruiker_id)
+            gebruiker.subjects.remove(instance)
\ No newline at end of file
diff --git a/api/serializers/vak.py b/api/serializers/vak.py
index 616156e8..9f37eba9 100644
--- a/api/serializers/vak.py
+++ b/api/serializers/vak.py
@@ -10,6 +10,9 @@ class Meta:
     def create(self, validated_data):
         students_data = validated_data.pop('students')
         teachers_data = validated_data.pop('teachers')
+        
+        validate_students_teachers(students_data, teachers_data)
+
         projects_data = validated_data.pop('projects')
         vak = Vak.objects.create(**validated_data)
         vak.students.set(students_data)
@@ -20,13 +23,15 @@ def create(self, validated_data):
     def update(self, instance, validated_data):
         instance.name = validated_data.pop('name')
 
-
         students_data = validated_data.pop('students', [])
         teachers_data = validated_data.pop('teachers', [])
+
+        validate_students_teachers(students_data, teachers_data)
+
         projects_data = validated_data.pop('projects', [])
-        instance.students.clear()
-        instance.teachers.clear()
-        instance.projects.clear()
+        clear(instance.students)
+        clear(instance.teachers)
+        clear(instance.projects)
 
         instance.students.set(students_data)
         instance.teachers.set(teachers_data)
@@ -35,3 +40,16 @@ def update(self, instance, validated_data):
         instance.save()
         
         return instance
+    
+def validate_students_teachers(students_data, teachers_data):
+    for student in students_data:
+        if student.is_lesgever:
+            raise serializers.ValidationError("Alle gebruikers in 'students' moeten studenten zijn")
+
+    for teacher in teachers_data:
+        if not teacher.is_lesgever:
+            raise serializers.ValidationError("Alle gebruikers in 'teachers' moeten lesgevers zijn")
+
+def clear(set):
+    for item in set.all(): 
+            set.remove(item)