diff --git a/CMakeLists.txt b/CMakeLists.txt
index fedc54f..e6411cd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -11,7 +11,7 @@ endif()
 set(CMAKE_CXX_STANDARD 17) #needed by libocore and libutils. -
 #set globally to match MAME's genie scripts.
 
-if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
+if(WIN32)
 add_compile_definitions(
   X64_WINDOWS_ABI
   CRLF=3
diff --git a/cmake_subdirs/expat/CMakeLists.txt b/cmake_subdirs/expat/CMakeLists.txt
index 5eb6c27..e72f2d6 100644
--- a/cmake_subdirs/expat/CMakeLists.txt
+++ b/cmake_subdirs/expat/CMakeLists.txt
@@ -38,7 +38,7 @@ add_compile_definitions(
 )
 endif()
 
-if(${CMAKE_SYSTEM_NAME} STREQUAL "Linux" OR CMAKE_SYSTEM_NAME STREQUAL "Android")
+if(UNIX)
 add_compile_definitions(
     HAVE_DLFCN_H
     HAVE_FCNTL_H
diff --git a/cmake_subdirs/ocore_sdl/CMakeLists.txt b/cmake_subdirs/ocore_sdl/CMakeLists.txt
index 47707bf..e2a4052 100644
--- a/cmake_subdirs/ocore_sdl/CMakeLists.txt
+++ b/cmake_subdirs/ocore_sdl/CMakeLists.txt
@@ -21,7 +21,7 @@ ${CMAKE_SOURCE_DIR}/src/osd/modules/lib/osd_getenv.cpp #instead of osdlib_${targ
 ${CMAKE_SOURCE_DIR}/src/osd/modules/lib/osdlib.h
 )
 
-if(CMAKE_SYSTEM_NAME STREQUAL "Linux" OR CMAKE_SYSTEM_NAME STREQUAL "Android")
+if(UNIX)
 target_sources(ocore_sdl PRIVATE
     ${CMAKE_SOURCE_DIR}/src/osd/modules/file/posixdir.cpp
     ${CMAKE_SOURCE_DIR}/src/osd/modules/file/posixfile.cpp
@@ -29,7 +29,7 @@ target_sources(ocore_sdl PRIVATE
     ${CMAKE_SOURCE_DIR}/src/osd/modules/file/posixptty.cpp
     ${CMAKE_SOURCE_DIR}/src/osd/modules/file/posixsocket.cpp
 )
-elseif(CMAKE_SYSTEM_NAME STREQUAL "Windows")
+elseif(WIN32)
 target_sources(ocore_sdl PRIVATE
     ${CMAKE_SOURCE_DIR}/src/osd/modules/file/windir.cpp
     ${CMAKE_SOURCE_DIR}/src/osd/modules/file/winfile.cpp