Index: CMakeLists.txt
--- CMakeLists.txt.orig
+++ CMakeLists.txt
@@ -162,7 +162,7 @@ set(wartool_LIBS ${pudconvert_LIBS} ${PNG_LIBRARIES} $
 
 if(WIN32 AND MSVC)
 	add_definitions(-D_CRT_SECURE_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE=1)
-else()
+elseif(NOT CMAKE_SYSTEM_NAME MATCHES BSD)
 	include(CheckCXXSourceCompiles)
 	set(FS_SRC "
 	#include <experimental/filesystem> 
