--- layers/CMakeLists.txt.orig	2018-07-30 17:53:08 UTC
+++ layers/CMakeLists.txt
@@ -23,7 +23,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
     set(DisplayServer Win32)
 elseif(CMAKE_SYSTEM_NAME STREQUAL "Android")
     add_definitions(-DVK_USE_PLATFORM_ANDROID_KHR -DVK_USE_PLATFORM_ANDROID_KHX)
-elseif(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+elseif(UNIX AND NOT APPLE)
     if(BUILD_WSI_XCB_SUPPORT)
         add_definitions(-DVK_USE_PLATFORM_XCB_KHR -DVK_USE_PLATFORM_XCB_KHX)
     endif()
@@ -131,7 +131,7 @@ if(WIN32)
         add_custom_target(vk_validation_error_messages ALL COMMAND copy ${src_val_msgs} ${dst_val_msgs} VERBATIM)
         set_target_properties(vk_validation_error_messages PROPERTIES FOLDER ${LAYERS_HELPER_FOLDER})
     endif()
-elseif(${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
+ elseif(UNIX AND NOT APPLE)
     # extra setup for out-of-tree builds
     if(NOT (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_CURRENT_BINARY_DIR))
         foreach(config_file ${LAYER_JSON_FILES})