diff --git a/scripts/kwboot.c b/scripts/kwboot.c
index e068660..46328d8 100644
--- a/scripts/kwboot.c
+++ b/scripts/kwboot.c
@@ -376,21 +376,23 @@
 
 	} while (c == NAK && retries-- > 0);
 
-	rc = -1;
+	if (!rc) {
+		rc = -1;
 
-	switch (c) {
-	case ACK:
-		rc = 0;
-		break;
-	case NAK:
-		errno = EBADMSG;
-		break;
-	case CAN:
-		errno = ECANCELED;
-		break;
-	default:
-		errno = EPROTO;
-		break;
+		switch (c) {
+		case ACK:
+			rc = 0;
+			break;
+		case NAK:
+			errno = EBADMSG;
+			break;
+		case CAN:
+			errno = ECANCELED;
+			break;
+		default:
+			errno = EPROTO;
+			break;
+		}
 	}
 
 	return rc;