A new 'Harry Potter' fan theory has emerged and left fans baffled.
Super-fans of the wizarding franchise have uncovered an issue with the plot of the films which is all to do with the material the students of Hogwarts write on.
In the movie series the characters appear to only write on parchment, which is an expensive material made of animal skin.
A Reddit user, by the name steampunk_penguin_, revealed in a post that they don't understand how all the students at the magical school afford to buy all their parchment.
The user worked out that the average wizard has to pay for their own material and needs around 300 scrolls a year - and so would simply not be able to afford it.
The user summed up their theory by stating the most logical answer to it all is simply: "this is Harry Potter, so boom, MAGIC!"