Inocuous SQL error when rotating an image

When rotating an image, I get the following error message:

user warning: Column 'nid' in where clause is ambiguous query: UPDATE files f JOIN image i ON f.fid=i.fid SET filesize=790819 WHERE filename='_original' AND nid=2460 in /home/.primorose/gwolf/drupal6/sites/gwolf.org/modules/acidfree/types/acidfree_image/acidfree_image.module on line 107.

Of course, what is missing is that both the image and the files tables have a nid field — This query should read:

UPDATE files f JOIN image i ON f.fid=i.fid SET filesize=790819 WHERE filename='_original' AND i.nid=2460

Keep in mind that files' nid field is often kept null, when a file does not belong to a specific node AFAICT.