Don't look at string[length - 1] if length == 0.

1 files changed, 2 insertions, 2 deletions

diff --git a/client.c b/client.c
index 82e43992..e1bd47c2 100644
--- a/client.c
+++ b/client.c
@@ -575,7 +575,7 @@ client_dispatch_wait(void *data0)
 			imsg_free(&imsg);
 			return (-1);
 		case MSG_SHELL:
-			if (data[datalen - 1] != '\0')
+			if (datalen == 0 || data[datalen - 1] != '\0')
 				fatalx("bad MSG_SHELL string");
 
 			clear_signals(0);
@@ -659,7 +659,7 @@ client_dispatch_attached(void)
 			kill(getpid(), SIGTSTP);
 			break;
 		case MSG_LOCK:
-			if (data[datalen - 1] != '\0')
+			if (datalen == 0 || data[datalen - 1] != '\0')
 				fatalx("bad MSG_LOCK string");
 
 			system(data);