diff --git a/mesh/mesh-defs.h b/mesh/mesh-defs.h
index 25ce012..a12acaf 100644
--- a/mesh/mesh-defs.h
+++ b/mesh/mesh-defs.h
@@ -12,6 +12,15 @@
 #define MESH_AD_TYPE_NETWORK	0x2A
 #define MESH_AD_TYPE_BEACON	0x2B
 
+/*
+ * MshPRT_v1.1, section 3.3.1 / Core_v5.3, section 2.3.1.3
+ * Maximum length of AdvData without 'Length' field (30)
+ */
+#define MESH_AD_MAX_LEN		(BT_AD_MAX_DATA_LEN - 1)
+
+/* Max size of a Network PDU, prior prepending AD type (29)*/
+#define MESH_NET_MAX_PDU_LEN	(MESH_AD_MAX_LEN - 1)
+
 #define FEATURE_RELAY	1
 #define FEATURE_PROXY	2
 #define FEATURE_FRIEND	4
diff --git a/mesh/mesh-io-generic.c b/mesh/mesh-io-generic.c
index 1ec4f37..0875a35 100644
--- a/mesh/mesh-io-generic.c
+++ b/mesh/mesh-io-generic.c
@@ -19,6 +19,7 @@
 #include <ell/ell.h>
 
 #include "monitor/bt.h"
+#include "src/shared/ad.h"
 #include "src/shared/hci.h"
 #include "src/shared/mgmt.h"
 #include "lib/bluetooth.h"
@@ -52,7 +53,7 @@ struct tx_pkt {
 	struct mesh_io_send_info	info;
 	bool				delete;
 	uint8_t				len;
-	uint8_t				pkt[30];
+	uint8_t				pkt[MESH_AD_MAX_LEN];
 };
 
 struct tx_pattern {
diff --git a/mesh/mesh-io-mgmt.c b/mesh/mesh-io-mgmt.c
index 4ca7ff9..065067f 100644
--- a/mesh/mesh-io-mgmt.c
+++ b/mesh/mesh-io-mgmt.c
@@ -23,6 +23,7 @@
 #include "lib/bluetooth.h"
 #include "lib/bluetooth.h"
 #include "lib/mgmt.h"
+#include "src/shared/ad.h"
 #include "src/shared/mgmt.h"
 
 #include "mesh/mesh-defs.h"
@@ -60,7 +61,7 @@ struct tx_pkt {
 	struct mesh_io_send_info	info;
 	bool				delete;
 	uint8_t				len;
-	uint8_t				pkt[30];
+	uint8_t				pkt[MESH_AD_MAX_LEN];
 };
 
 struct tx_pattern {
diff --git a/mesh/mesh-io-unit.c b/mesh/mesh-io-unit.c
index 936f5a9..f9a5aaa 100644
--- a/mesh/mesh-io-unit.c
+++ b/mesh/mesh-io-unit.c
@@ -22,6 +22,8 @@
 #include <time.h>
 #include <ell/ell.h>
 
+#include "src/shared/ad.h"
+
 #include "mesh/mesh-defs.h"
 #include "mesh/dbus.h"
 #include "mesh/mesh-io.h"
@@ -59,7 +61,7 @@ struct tx_pkt {
 	struct mesh_io_send_info	info;
 	bool				delete;
 	uint8_t				len;
-	uint8_t				pkt[30];
+	uint8_t				pkt[MESH_AD_MAX_LEN];
 };
 
 struct tx_pattern {
diff --git a/mesh/net-keys.c b/mesh/net-keys.c
index 22ab5b6..9b11bb7 100644
--- a/mesh/net-keys.c
+++ b/mesh/net-keys.c
@@ -16,6 +16,8 @@
 
 #include <ell/ell.h>
 
+#include "src/shared/ad.h"
+
 #include "mesh/mesh-defs.h"
 #include "mesh/util.h"
 #include "mesh/crypto.h"
@@ -74,8 +76,8 @@ static struct l_queue *keys;
 static uint32_t last_flooding_id;
 
 /* To avoid re-decrypting same packet for multiple nodes, cache and check */
-static uint8_t cache_pkt[29];
-static uint8_t cache_plain[29];
+static uint8_t cache_pkt[MESH_NET_MAX_PDU_LEN];
+static uint8_t cache_plain[MESH_NET_MAX_PDU_LEN];
 static size_t cache_len;
 static size_t cache_plainlen;
 static uint32_t cache_id;
diff --git a/mesh/net.c b/mesh/net.c
index d711f80..cf4f337 100644
--- a/mesh/net.c
+++ b/mesh/net.c
@@ -19,6 +19,8 @@
 
 #include <ell/ell.h>
 
+#include "src/shared/ad.h"
+
 #include "mesh/mesh-defs.h"
 #include "mesh/util.h"
 #include "mesh/crypto.h"
@@ -203,7 +205,7 @@ struct oneshot_tx {
 	uint16_t interval;
 	uint8_t cnt;
 	uint8_t size;
-	uint8_t packet[30];
+	uint8_t packet[MESH_AD_MAX_LEN];
 };
 
 struct net_beacon_data {
@@ -2246,7 +2248,7 @@ static bool match_by_dst(const void *a, const void *b)
 
 static void send_relay_pkt(struct mesh_net *net, uint8_t *data, uint8_t size)
 {
-	uint8_t packet[30];
+	uint8_t packet[MESH_AD_MAX_LEN];
 	struct mesh_io *io = net->io;
 	struct mesh_io_send_info info = {
 		.type = MESH_IO_TIMING_TYPE_GENERAL,
@@ -3130,8 +3132,7 @@ static bool send_seg(struct mesh_net *net, uint8_t cnt, uint16_t interval,
 {
 	struct mesh_subnet *subnet;
 	uint8_t seg_len;
-	uint8_t gatt_data[30];
-	uint8_t *packet = gatt_data;
+	uint8_t packet[MESH_AD_MAX_LEN];
 	uint8_t packet_len;
 	uint8_t segN = SEG_MAX(msg->segmented, msg->len);
 	uint16_t seg_off = SEG_OFF(segO);
@@ -3193,7 +3194,7 @@ void mesh_net_send_seg(struct mesh_net *net, uint32_t net_key_id,
 			uint16_t src, uint16_t dst, uint32_t hdr,
 			const void *seg, uint16_t seg_len)
 {
-	uint8_t packet[30];
+	uint8_t packet[MESH_AD_MAX_LEN];
 	uint8_t packet_len;
 	bool segmented = !!((hdr >> SEG_HDR_SHIFT) & 0x1);
 	uint8_t key_aid = (hdr >> KEY_HDR_SHIFT) & KEY_ID_MASK;
@@ -3353,7 +3354,7 @@ void mesh_net_ack_send(struct mesh_net *net, uint32_t net_key_id,
 	uint32_t hdr;
 	uint8_t data[7];
 	uint8_t pkt_len;
-	uint8_t pkt[30];
+	uint8_t pkt[MESH_AD_MAX_LEN];
 
 	/*
 	 * MshPRFv1.0.1 section 3.4.5.2, Interface output filter:
@@ -3400,7 +3401,7 @@ void mesh_net_transport_send(struct mesh_net *net, uint32_t net_key_id,
 				uint16_t msg_len)
 {
 	uint8_t pkt_len;
-	uint8_t pkt[30];
+	uint8_t pkt[MESH_AD_MAX_LEN];
 	bool result = false;
 
 	if (!net->src_addr)
@@ -3416,7 +3417,7 @@ void mesh_net_transport_send(struct mesh_net *net, uint32_t net_key_id,
 		ttl = net->default_ttl;
 
 	/* Range check the Opcode and msg length*/
-	if (*msg & 0xc0 || (9 + msg_len + 8 > 29))
+	if (*msg & 0xc0 || (9 + msg_len + 8 > MESH_NET_MAX_PDU_LEN))
 		return;
 
 	/*