--- a/src/nfacct.c
+++ b/src/nfacct.c
@@ -211,19 +211,61 @@
 	return 0;
 }
 
+static const char *fmt_options[FMT_MAX + 1] =	{ 
+						"def","3pl","iec","kib",
+						"mib","gib","tib","pib","eib",
+						"si","kb","mb", "gb", "tb",
+						"pb","eb",""
+						};
+
+static uint32_t nfacct_parse_format_options(const char *argv) {
+	char *ptr;
+	char *tmp = strdup(argv);
+	int i, j;
+	enum nfacct_format fmt[2] = { FMT_MAX, FMT_MAX };
+
+	for (i = 0; i <= 2 && tmp != NULL; i++) {
+		ptr = strsep(&tmp, ",");
+
+		if (ptr != NULL && strlen(ptr) == 0) {
+			fmt[i] = FMT_DEFAULT;
+		} else {
+			for (j = 0; j <= FMT_MAX && 
+			      strncmp(ptr, fmt_options[j], 3) != 0; j++) { ; }
+
+			if (j >= FMT_MAX)
+				break;
+
+			fmt[i] = j;
+		}
+	}
+
+	if (i > 2 || j >= FMT_MAX)
+		return -1;
+
+	if (fmt[0] == FMT_MAX) 
+		fmt[0] = fmt[1];
+
+	if (fmt[1] == FMT_MAX)
+		fmt[1] = fmt[0];
+
+	return (fmt[0] << 4) | fmt[1];
+}
+
 static int nfacct_cmd_add(int argc, char *argv[])
 {
 	struct mnl_socket *nl;
 	char buf[MNL_SOCKET_BUFFER_SIZE];
 	struct nlmsghdr *nlh;
 	uint32_t portid, seq;
+	uint32_t fmt;
 	struct nfacct *nfacct;
 	int ret;
 
 	if (argc < 3) {
 		nfacct_perror("missing object name");
 		return -1;
-	} else if (argc > 3) {
+	} else if (argc > 4) {
 		nfacct_perror("too many arguments");
 		return -1;
 	}
@@ -236,6 +278,15 @@
 
 	nfacct_attr_set(nfacct, NFACCT_ATTR_NAME, argv[2]);
 
+	if (argc == 4 && argv[3] != NULL) {
+		fmt = nfacct_parse_format_options(argv[3]);
+		if (fmt == -1) {
+			nfacct_perror("packets/bytes format wrong");
+			return -1;
+		}
+		nfacct_attr_set(nfacct, NFACCT_ATTR_FMT, &fmt);
+	}
+
 	seq = time(NULL);
 	nlh = nfacct_nlmsg_build_hdr(buf, NFNL_MSG_ACCT_NEW,
 				     NLM_F_CREATE | NLM_F_ACK, seq);