diff --git a/requirements/production.txt b/requirements/production.txt
index 273e15c71ee53d8d4e3b2f06dd75e73ff337c457..d4403006c713efb94b3f60beeb43b6b2144d0cb3 100644
--- a/requirements/production.txt
+++ b/requirements/production.txt
@@ -11,7 +11,7 @@ diff-match-patch==20121119  # via django-import-export
 django-import-export==1.0.0
 django-social-authsch==0.1
 django-solo==1.1.3
-django==2.0.1
+django>=2.0.10
 djangorestframework==3.7.7
 et-xmlfile==1.0.1         # via openpyxl
 gunicorn==19.7.1
@@ -23,14 +23,14 @@ openpyxl==2.5.0           # via tablib
 pyjwt==1.5.3              # via social-auth-core
 python3-openid==3.1.0     # via social-auth-core
 pytz==2017.3              # via django
-pyyaml==3.12              # via tablib
+pyyaml>=4.2b1              # via tablib
 requests-oauthlib==0.8.0  # via social-auth-core
-requests==2.18.4          # via requests-oauthlib, social-auth-core
+requests>=2.20.0         # via requests-oauthlib, social-auth-core
 six==1.11.0               # via social-auth-app-django, social-auth-core
 social-auth-app-django==2.1.0  # via django-social-authsch
 social-auth-core==1.6.0   # via django-social-authsch, social-auth-app-django
 tablib==0.12.1            # via django-import-export
 unicodecsv==0.14.1        # via tablib
-urllib3==1.22             # via requests
+urllib3>=1.23             # via requests
 xlrd==1.1.0               # via tablib
 xlwt==1.3.0               # via tablib
diff --git a/src/common/email.py b/src/common/email.py
index 96b34ca8c412cbc4d36bdf9340f1296fc31d77e5..0c8d6b351c9b33fa732ae13f52a03d5fb57519ef 100644
--- a/src/common/email.py
+++ b/src/common/email.py
@@ -14,7 +14,7 @@ def read_email(name):
 def registration(user):
     subject = "KszkĂŠpzĂŠs regisztrĂĄciĂł"
     message = read_email('registration.txt')
-    message = str.format(message %{'name': user.get_full_name()})
+    message = str.format(message % {'name': user.get_full_name()})
     send_mail(subject, message, sender_email, [user.email, ])
 
 
@@ -47,5 +47,5 @@ def homework_corrected(user, title, accepted):
     else:
         status = 'HibĂĄs'
     message = read_email('homework_corrected.txt')
-    message = str.format(message % {'name': user.get_full_name(), 'link': link, 'status': status, 'title': title })
+    message = str.format(message % {'name': user.get_full_name(), 'link': link, 'status': status, 'title': title})
     send_mail(subject, message, sender_email, [user.email, ])
diff --git a/src/homework/serializers.py b/src/homework/serializers.py
index c6e4fde20ad2289c20456d7e5a7909bc47c87f2b..3ee662e264b2710475a78c9b0538a2ad8b2770cb 100755
--- a/src/homework/serializers.py
+++ b/src/homework/serializers.py
@@ -64,7 +64,7 @@ class SolutionSerializer(serializers.ModelSerializer):
         return value
 
     def update(self, instance, validated_data):
-        if instance.corrected == False and validated_data.get('corrected', instance.corrected) == True:
+        if instance.corrected is not True and validated_data.get('corrected', instance.corrected) is True:
             email.homework_corrected(
                 instance.created_by.user,
                 instance.task.title,
@@ -76,4 +76,3 @@ class SolutionSerializer(serializers.ModelSerializer):
         profile = CurrentUserMiddleware.get_current_user_profile()
         models.Solution.objects.filter(created_by=profile, task=validated_data['task']).delete()
         return super().create(validated_data)
-