diff --git a/shell/ash.c b/shell/ash.c
index 9681111..22c7260 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -12967,7 +12967,7 @@
 	exitcode = 0;
 	while (*ap) {
 		signo = get_signum(*ap);
-		if (signo < 0) {
+		if (signo < 0 || signo >= NSIG) {
 			/* Mimic bash message exactly */
 			ash_msg("%s: invalid signal specification", *ap);
 			exitcode = 1;