I've recently installed cygwin64 on my Windows 10 machine in an attempt to build a project using cmake (Through CLion).

The project has lz4 as a dependency and when running the cygwin setup, there's a gui where you can select packages to install.

One of the default packages is liblz4_1 so I made sure it remained selected and installed the packages.

However when trying to build my project, I get a fatal cmake error 'fatal error: lz4.h: No such file or directory'.

So I gather cmake doesn't know where to look for the header files, and it turns out neither do I.

I've searched through C:\cygwin64\usr\include and in fact used Windows search through the entire C:\cygwin64 folder and could not find any file with lz4 in its name.

So, does anyone know where the packages installed during setup actually get stored?

  • 1
    They should be contained within the Cygwin64 directory.
    – Ramhound
    Oct 12, 2021 at 19:00
  • @Ramhound in usr\include ? because its not there. Oct 12, 2021 at 19:11

2 Answers 2


You need to install the liblz4-devel package. You can use cygcheck to identify the package containing a specific file

$ cygcheck -p usr/include/lz4.h
Found 1 matches for usr/include/lz4.h
liblz4-devel-1.7.5-1 - liblz4-devel: LZ4 de/compressor

They were in 'usr\include', I just had to install the package labeled plain 'lz4'.

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