makemigrations keeps detecting changes to my Attachment model

Hello,

I have made an Attachment model that saves files to my filesystem using a custom storage (that doesn't save if the file already exists and uses that file instead, and ./manage.py makemigrations always gives the following:

 

Migrations for 'backend':
  backend/migrations/0012_auto_20170414_0543.py:
    - Alter field file on attachment

 

I don't know why this is happening, because I've already made my storage class and my Attachment model deconstructible.
Code for my Attachment model: https://dpaste.de/qy2Y
Code for my Storage: https://dpaste.de/KpY3
Any help is appreciated.

 

Best Regards,

m712 - Developer