diff --git a/compiler-rt/lib/safestack/safestack.cc b/compiler-rt/lib/safestack/safestack.cc
--- a/compiler-rt/lib/safestack/safestack.cc
+++ b/compiler-rt/lib/safestack/safestack.cc
@@ -83,7 +83,7 @@
 const unsigned kDefaultUnsafeStackSize = 0x2800000;
 
 /// Runtime page size obtained through sysconf
-unsigned pageSize;
+unsigned pageSize = 4096;
 
 // Per-thread unsafe stack information. It's not frequently accessed, so there
 // it can be kept out of the tcb in normal thread-local variables.
@@ -264,11 +264,9 @@
 __attribute__((constructor(0)))
 #endif
 void __safestack_init() {
-  pageSize = sysconf(_SC_PAGESIZE);
-
   // Determine the stack size for the main thread.
   size_t size = kDefaultUnsafeStackSize;
-  size_t guard = 4096;
+  size_t guard = pageSize;
 
   struct rlimit limit;
   if (getrlimit(RLIMIT_STACK, &limit) == 0 && limit.rlim_cur != RLIM_INFINITY)
@@ -276,8 +274,8 @@
 
   // Allocate unsafe stack for main thread
   void *addr = unsafe_stack_alloc(size, guard);
-
   unsafe_stack_setup(addr, size, guard);
+  pageSize = sysconf(_SC_PAGESIZE);
 
   // Setup the cleanup handler
   pthread_key_create(&thread_cleanup_key, thread_cleanup_handler);