diff --git a/arch/x86/kernel/syscall.c b/arch/x86/kernel/syscall.c
index 0b3bb814..71a5fa28 100644
--- a/arch/x86/kernel/syscall.c
+++ b/arch/x86/kernel/syscall.c
@@ -110,7 +110,7 @@ SYSCALL_DECLARE(rt_sigaction)
 	struct k_sigaction new_sa, old_sa;
 	int rc;
 
-	if(sig == SIGKILL || sig == SIGSTOP)
+	if(sig == SIGKILL || sig == SIGSTOP || sig <= 0 || sig > 64)
 		return -EINVAL;
 	if (sigsetsize != sizeof(sigset_t))
 		return -EINVAL;