diff --git a/libc/include/sys/ucontext.h b/libc/include/sys/ucontext.h
index 20dcdd51f..d6c6b4317 100644
--- a/libc/include/sys/ucontext.h
+++ b/libc/include/sys/ucontext.h
@@ -198,6 +198,7 @@ typedef struct ucontext {
   stack_t uc_stack;
   mcontext_t uc_mcontext;
   sigset_t uc_sigmask;
+  char __padding[128 - sizeof(sigset_t)];
 } ucontext_t;
 
 #elif defined(__mips64__)