diff --git a/commands/crc.c b/commands/crc.c
index 01fedd7..8ce97da 100644
--- a/commands/crc.c
+++ b/commands/crc.c
@@ -108,6 +108,8 @@
 			verify = 1;
 			vcrc = simple_strtoul(optarg, NULL, 0);
 			break;
+		default:
+			return COMMAND_ERROR_USAGE;
 		}
 	}