CMake was displaying some warnings about a space in argument used for asciidoc command: -a date=`date "+%F"` Warning displayed: CMake Warning (dev) in doc/en/CMakeLists.txt: Syntax Warning in cmake code at /path/to/doc/en/CMakeLists.txt:41:82 Argument not separated from preceding token by whitespace. This warning is for project developers. Use -Wno-dev to suppress it.