Disclaimer: Most native build tools have poor support for escaping certain values. CMake has work-arounds for many cases but some values may just not be possible to pass correctly. If a value does not seem to be escaped correctly, do not attempt to work-around the problem by adding escape sequences to the value. Your work-around may break in a future version of CMake that has improved escape support. Instead consider defining the macro in a (configured) header file. Then report the limitation. Known limitations include:: # - broken almost everywhere ; - broken in VS IDE 7.0 and Borland Makefiles , - broken in VS IDE % - broken in some cases in NMake & | - broken in some cases on MinGW ^ < > \" - broken in most Make tools on Windows CMake does not reject these values outright because they do work in some cases. Use with caution.