Here's my matrix defining some of the variables I will likely often change:

environment:
  matrix:
    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
      ROOT: c:\dev\source
      SCRIPTS: '%ROOT%\scripts'
      CONFIG: 'Release'
      OS: 'windows'
      PLAT: 'x86_64'
      PRODUCT_NAME: Ember
      RELEASE_VERSION: 0.0
      OUTPUT_FOLDER: 'bin\%CONFIG%-%OS%-%PLAT%'

For some reason though, the system is appending "_NT" string to my %OS% path when I'm trying to concatenate it with other paths and that is preventing me to use the variable to compose the actual path I have to reach.

log

[00:05:55] echo %FILE_VERSION%
[00:05:55] v0.0.45-beta
[00:05:55] echo %OS%
[00:05:55] windows
[00:05:55] echo %CONFIG%-%OS%-%PLAT%
[00:05:55] Release-windows-x86_64
[00:05:55] echo %OUTPUT_FOLDER%
[00:05:55] bin\Release-Windows_NT-x86_64
[00:05:55] echo %ROOT%\%OUTPUT_FOLDER%
[00:05:55] c:\dev\source\bin\Release-Windows_NT-x86_64
[00:05:55] ren  %OUTPUT_FOLDER%\installers\%PRODUCT_NAME%Setup.exe "%PRODUCT_NAME%-%FILE_VERSION% setup.exe"
[00:05:56] The system cannot find the path specified.
[00:05:56] Command exited with code 1

Does anyone have a solution for this that is not to hard-code "windows" everywhere?