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
@@ -228,7 +228,7 @@
   }
 
   SFS_CHECK(size);
-  SFS_CHECK((size & (kStackAlign - 1)) == 0);
+  size = RoundUpTo(size, kStackAlign);
   SFS_CHECK((guard & (pageSize - 1)) == 0);
 
   void *addr = unsafe_stack_alloc(size, guard);