--- Libc/Libc-391.5.18/pthreads/pthread.c
+++ Libc/Libc-391/pthreads/pthread.c
@@ -156,7 +156,7 @@
 
 #if defined(__ppc__) || defined(__ppc64__)
 static const vm_address_t PTHREAD_STACK_HINT = 0xF0000000;
-#elif defined(__i386__) || defined(__x86_64__)
+#elif defined(__i386__)
 static const vm_address_t PTHREAD_STACK_HINT = 0xB0000000;
 #else
 #error Need to define a stack address hint for this architecture