diff -up netkit-ftp-0.17/ftp/cmds.c.acct_ovl netkit-ftp-0.17/ftp/cmds.c
--- netkit-ftp-0.17/ftp/cmds.c.acct_ovl	2011-09-09 15:36:36.087956561 +0200
+++ netkit-ftp-0.17/ftp/cmds.c	2011-09-09 15:41:16.457495370 +0200
@@ -1837,8 +1837,7 @@ account(int argc, char *argv[])
 		while (argc > 1) {
 			--argc;
 			++argv;
-			strncat(buf, *argv, sizeof(buf)-strlen(buf));
-			buf[sizeof(buf)-1] = 0;
+			strncat(buf, *argv, sizeof(buf)-strlen(buf)-1);
 		}
 		ap = buf;
 	}