On Windows, `NPM_FILE_PATTERNS` only works if you use backslash separators like so: ```python NPM_FILE_PATTERNS = { "bootstrap": [ "dist\\css\\bootstrap.min.css", "dist\\css\\bootstrap.min.css.map", "dist\\js\\bootstrap.bundle.min.js", "dist\\js\\bootstrap.bundle.min.js.map", ], } ``` This is problematic when you want to write portable code. We should be able to use forward slash on all operating systems. Let me know if you want me to open a Pull Request.