I don't know if Windows has case-sensitive environment variables, but I would expect GNU to decide to completely switch to English using LANG=C If this does not help, try LC_ALL=C or check if there is a locale command in the mingw environment that can help you show the exact locale settings.
If you set these environment variables from the mingw bash environment, make sure that the shell exports these environment variables to running processes (for example, ask make ). That is, either set the values using export FOO=bar , or export them using a separate export FOO after setting them using FOO=bar .
(I assume that mingw behaves like a standard GNU environment when it comes to locales.)
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