diff --git a/arch/x86/kernel/syscall.c b/arch/x86/kernel/syscall.c
index 34f9e582..b6680537 100644
--- a/arch/x86/kernel/syscall.c
+++ b/arch/x86/kernel/syscall.c
@@ -110,6 +110,8 @@ SYSCALL_DECLARE(rt_sigaction)
 	struct k_sigaction new_sa, old_sa;
 	int rc;
 
+	if(sig == SIGKILL || sig == SIGSTOP)
+		return -EINVAL;
 	if (sigsetsize != sizeof(sigset_t))
 		return -EINVAL;