diff --git a/arch/x86/kernel/syscall.c b/arch/x86/kernel/syscall.c
index 029626ae..dea1ca0f 100644
--- a/arch/x86/kernel/syscall.c
+++ b/arch/x86/kernel/syscall.c
@@ -591,7 +591,8 @@ do_signal(unsigned long rc, void *regs0, struct thread *thread, struct sig_pendi
 		regs->gpr.rip = (unsigned long)k->sa.sa_handler;
 		regs->gpr.rsp = (unsigned long)usp;
 
-		thread->sigmask.__val[0] |= pending->sigmask.__val[0];
+		if(!(k->sa.sa_flags & SA_NODEFER))
+			thread->sigmask.__val[0] |= pending->sigmask.__val[0];
 		kfree(pending);
 		ihk_mc_spinlock_unlock(&thread->sigcommon->lock, irqstate);
 	}