diff --git a/lib/zclient.c b/lib/zclient.c
index 91dbe30a09..a135d18744 100644
--- a/lib/zclient.c
+++ b/lib/zclient.c
@@ -293,6 +293,10 @@ int zclient_send_message(struct zclient *zclient)
 	return 0;
 }
 
+/*
+ * If we add more data to this structure please ensure that
+ * struct zmsghdr in lib/zclient.h is updated as appropriate.
+ */
 void zclient_create_header(struct stream *s, uint16_t command, vrf_id_t vrf_id)
 {
 	/* length placeholder, caller can update */
diff --git a/lib/zclient.h b/lib/zclient.h
index 5f9edc36ff..2131d4d47a 100644
--- a/lib/zclient.h
+++ b/lib/zclient.h
@@ -298,7 +298,8 @@ struct zmsghdr {
 	uint8_t version;
 	vrf_id_t vrf_id;
 	uint16_t command;
-};
+} __attribute__((packed));
+#define ZAPI_HEADER_CMD_LOCATION offsetof(struct zmsghdr, command)
 
 struct zapi_nexthop {
 	enum nexthop_types_t type;
diff --git a/zebra/zserv.c b/zebra/zserv.c
index c008441d6a..b0991e98f8 100644
--- a/zebra/zserv.c
+++ b/zebra/zserv.c
@@ -240,7 +240,7 @@ static int zserv_write(struct thread *thread)
 	if (cache->tail) {
 		msg = cache->tail;
 		stream_set_getp(msg, 0);
-		wcmd = stream_getw_from(msg, 6);
+		wcmd = stream_getw_from(msg, ZAPI_HEADER_CMD_LOCATION);
 	}
 
 	while (stream_fifo_head(cache)) {