diff --git a/amadeus/permissions.py b/amadeus/permissions.py
index 78bb281..c7486de 100644
--- a/amadeus/permissions.py
+++ b/amadeus/permissions.py
@@ -10,10 +10,10 @@ def has_subject_permissions(user, subject):
 	if user.is_staff:
 		return True
 
-	if user in subject.professor.all():
+	if subject.professor.filter(id = user.id).exists():
 		return True
 
-	if user in subject.category.coordinators.all():
+	if subject.category.coordinators.filter(id = user.id).exists():
 		return True
 
 	return False
diff --git a/subjects/utils.py b/subjects/utils.py
index 078fd01..a1d99f5 100644
--- a/subjects/utils.py
+++ b/subjects/utils.py
@@ -6,14 +6,14 @@ from django.db.models import Q
 
 def has_student_profile(user, category):
 	for subject in category.subject_category.all():
-		if user in subject.students.all() and subject.visible:
+		if subject.students.filter(id = user.id).exists() and subject.visible:
 			return True
 
 	return False
 
 def has_professor_profile(user, category):
 	for subject in category.subject_category.all():
-		if user in subject.professor.all() and subject.visible:
+		if subject.professor.filter(id = user.id).exists() and subject.visible:
 			return True
 
 	return False
--
libgit2 0.21.2