diff --git a/apps/cit.c b/apps/cit.c
index 2a3f6e7..6e2dc74 100644
--- a/apps/cit.c
+++ b/apps/cit.c
@@ -92,6 +92,10 @@ void *get_ts(void *a)
 		return NULL;
 	sprintf(fname, "/dev/dvb/adapter%u/ci%u", adapter, device);
 	fdi = open(fname, O_RDONLY);
+	if (fdi == -1) {
+		printf("Failed to open %s for read: %m\n", fname);
+		return NULL;
+	}
 
 	while (1) {
 		memset(buf, 0, 188*rnum);
@@ -123,6 +127,10 @@ int send(void)
 		return -1;
 	sprintf(fname, "/dev/dvb/adapter%u/ci%u", adapter, device);
 	fdo=open(fname, O_WRONLY);
+	if (fdo == -1) {
+		printf("Failed to open %s to write: %m\n", fname);
+		exit(2);
+	}
 
 	while (1) {
 		for (i=0; i<snum; i++) {
@@ -146,7 +154,7 @@ int send(void)
 int main(int argc, char **argv)
 {
 	pthread_t th;
-	
+
 	while (1) {
                 int option_index = 0;
 		int c;
@@ -179,13 +187,15 @@ int main(int argc, char **argv)
 			break;
 		case 'h':
 		default:
+			printf("cit -a<adapter> -d<device>\n");
+			exit(-1);
 			break;
-			
 		}
 	}
 	if (optind < argc) {
 		printf("Warning: unused arguments\n");
 	}
+	printf("adpter %d, device: %d\n", adapter, device);
 	memset(ts+8, 180, 0x5a);
 	pthread_create(&th, NULL, get_ts, NULL);
 	usleep(10000);