When using a dictionary file that contains the word I want ignored, cased correctly, codespell will not ignore it.

Contents of .dictionary:

ZUser

Command line output:

(app-service-link) [blake@bv-desktop app-service-link]$ codespell -S *.log -I .dictionary
./app/servicelink.py:23: ZUser ==> user
./app/servicelink.py:341: ZUser ==> user

However, if I change the case to zuser then it works as expected. This is contradictory to the help message for -I,

Words are case sensitive based on how they are written in the dictionary file

Using version 2.1.0 in Bash on Linux, normal text files with UTF8 encoding.