diff --git a/cansniffer.c b/cansniffer.c
index f6206c0..b907b5f 100644
--- a/cansniffer.c
+++ b/cansniffer.c
@@ -298,6 +298,8 @@ int main(int argc, char **argv)
 			break;
 
 		case '?':
+			print_usage(basename(argv[0]));
+			exit(0);
 			break;
 
 		default: