diff --git a/scripts/genout.cmake.in b/scripts/genout.cmake.in
index 3bbe453a0..01f12de2f 100644
--- a/scripts/genout.cmake.in
+++ b/scripts/genout.cmake.in
@@ -26,7 +26,12 @@ set(PLATFORM_C_FLAGS)
 if(APPLE)
   set(CMAKE_OSX_ARCHITECTURES "@CMAKE_OSX_ARCHITECTURES@")
   set(CMAKE_OSX_SYSROOT "@CMAKE_OSX_SYSROOT@")
-  set(PLATFORM_C_FLAGS -arch ${CMAKE_OSX_ARCHITECTURES} -isysroot ${CMAKE_OSX_SYSROOT})
+  if(CMAKE_OSX_ARCHITECTURES)
+    set(PLATFORM_C_FLAGS ${PLATFORM_C_FLAGS} -arch ${CMAKE_OSX_ARCHITECTURES})
+  endif()
+  if(CMAKE_OSX_SYSROOT)
+    set(PLATFORM_C_FLAGS ${PLATFORM_C_FLAGS} -isysroot ${CMAKE_OSX_SYSROOT})
+  endif()
 endif()
 
 get_filename_component(INPUTEXT "${INPUT}" EXT)