Index: uspace/app/mkext4/mkext4.c
===================================================================
--- uspace/app/mkext4/mkext4.c	(revision 9c3038d4dbd35b5a7471af62fa120a4a1bcc39a8)
+++ uspace/app/mkext4/mkext4.c	(revision 3ca0a2d4202b40e696aaefa529ce89543ef55f88)
@@ -124,8 +124,17 @@
 		}
 
+		if (str_cmp(*argv, "--help") == 0) {
+			syntax_print();
+			return 0;
+		}
+
 		if (str_cmp(*argv, "-") == 0) {
 			--argc;
 			++argv;
 			break;
+		} else {
+			printf(NAME ": Invalid argument: %s\n", *argv);
+			syntax_print();
+			return 1;
 		}
 	}