Try removing an empy UNIX clause so that the else clause matches UNIX. This is an attempt to fix #260 with almost no understanding of cmake.

alethzero/CMakeLists.txt

@@ -89,7 +89,6 @@ elseif ("${TARGET_PLATFORM}" STREQUAL "w64")
 	target_link_libraries(${EXECUTEABLE} crypt32)
 	target_link_libraries(${EXECUTEABLE} Qt5PlatformSupport)
 	set(CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS)
-elseif (UNIX)
 else ()
 	target_link_libraries(${EXECUTEABLE} boost_system)
 	target_link_libraries(${EXECUTEABLE} boost_filesystem)