diff --git Source/WTF/wtf/posix/OSAllocatorPOSIX.cpp Source/WTF/wtf/posix/OSAllocatorPOSIX.cpp
index a5eb8d44..051c439e 100644
--- Source/WTF/wtf/posix/OSAllocatorPOSIX.cpp
+++ Source/WTF/wtf/posix/OSAllocatorPOSIX.cpp
@@ -72,9 +72,11 @@ void* OSAllocator::reserveAndCommit(size_t bytes, Usage usage, bool writable, bo
 
     int flags = MAP_PRIVATE | MAP_ANON;
 #if OS(DARWIN)
+#if defined(MAP_JIT)
     if (executable)
         flags |= MAP_JIT;
 #endif
+#endif
 
 #if OS(DARWIN)
     int fd = usage;