--- Libc/Libc-1725.40.4/include/sys/cdefs.h
+++ Libc/Libc-1158.1.2/include/sys/cdefs.h
@@ -34,7 +34,7 @@
  */
 #include_next <sys/cdefs.h>
 #ifndef _LIBC_NO_FEATURE_VERIFICATION
-#if defined(__arm64__) || defined(__arm__) || defined(__i386__) || defined(__x86_64__)
+#if defined(__arm__) || defined(__i386__) || defined(__x86_64__)
 #  include "libc-features.h"
 #else
 #  error "Unknown architecture."
@@ -105,10 +105,13 @@
 
 extern int pthread_key_init_np(int, void (*)(void *));
 
-// Not needed anymore by this header, but other headers rely on this include being here.
 #include <TargetConditionals.h>
-
+#if TARGET_IPHONE_SIMULATOR
+/* Simulator keys are offset by 200 */
+#define	__LIBC_PTHREAD_KEY(x)		(210 + (x))
+#else
 #define	__LIBC_PTHREAD_KEY(x)		(10 + (x))
+#endif
 
 /*
  * Libc pthread key assignments