diff --git a/impl/src/layer2/layer2_structs.c b/impl/src/layer2/layer2_structs.c
index 8131be0..69d07fb 100644
--- a/impl/src/layer2/layer2_structs.c
+++ b/impl/src/layer2/layer2_structs.c
@@ -6,8 +6,8 @@
 
 size_t layer2_encode_packet_header(const layer2_packet_header_t *header, uint8_t *encoded)
 {
-	assert(header->src_addr_len < 4);
-	assert(header->dst_addr_len < 4);
+	assert(header->src_addr.length <= 4 && header->src_addr.length != 0);
+	assert(header->dst_addr.length <= 4 && header->dst_addr.length != 0);
 	assert(header->tx_seq_nr < 16);
 	assert(header->rx_seq_nr < 16);
 
@@ -16,18 +16,18 @@ size_t layer2_encode_packet_header(const layer2_packet_header_t *header, uint8_t
 	encoded[0] =
 		((uint8_t)header->msg_type & 0x7) << 5
 		| ((uint8_t)header->tx_request & 0x1) << 4
-		| (header->src_addr_len & 0x3) << 2
-		| (header->dst_addr_len & 0x3) << 0;
+		| ((header->src_addr.length-1) & 0x3) << 2
+		| ((header->dst_addr.length-1) & 0x3) << 0;
 
 	encoded[1] =
 		(header->tx_seq_nr & 0xF) << 4
 		| (header->rx_seq_nr & 0xF) << 0;
 
-	memcpy(encoded + encoded_size, header->src_addr, 2 * header->src_addr_len);
-	encoded_size += 2 * header->src_addr_len;
+	memcpy(encoded + encoded_size, header->src_addr.addr, 2 * header->src_addr.length);
+	encoded_size += 2 * header->src_addr.length;
 
-	memcpy(encoded + encoded_size, header->dst_addr, 2 * header->dst_addr_len);
-	encoded_size += 2 * header->dst_addr_len;
+	memcpy(encoded + encoded_size, header->dst_addr.addr, 2 * header->dst_addr.length);
+	encoded_size += 2 * header->dst_addr.length;
 
 	return encoded_size;
 }
@@ -37,14 +37,14 @@ bool layer2_decode_packet_header(const uint8_t *encoded, layer2_packet_header_t
 {
 	header->msg_type = (encoded[0] >> 5) & 0x7;
 	header->tx_request = (encoded[0] & 0x10) != 0;
-	header->src_addr_len = (encoded[0] >> 2) & 0x3;
-	header->dst_addr_len = (encoded[0] >> 0) & 0x3;
+	header->src_addr.length = (encoded[0] >> 2) & 0x3 + 1;
+	header->dst_addr.length = (encoded[0] >> 0) & 0x3 + 1;
 
 	header->tx_seq_nr = (encoded[1] >> 4) & 0xF;
 	header->tx_seq_nr = (encoded[1] >> 0) & 0xF;
 
-	memcpy(header->src_addr, encoded + 2, 2 * header->src_addr_len);
-	memcpy(header->dst_addr, encoded + 2 + 2 * header->src_addr_len, 2 * header->dst_addr_len);
+	memcpy(header->src_addr.addr, encoded + 2, 2 * header->src_addr.length);
+	memcpy(header->dst_addr.addr, encoded + 2 + 2 * header->src_addr.length, 2 * header->dst_addr.length);
 
 	return true;
 }
diff --git a/impl/src/layer2/layer2_structs.h b/impl/src/layer2/layer2_structs.h
index 8a15eb0..3345b21 100644
--- a/impl/src/layer2/layer2_structs.h
+++ b/impl/src/layer2/layer2_structs.h
@@ -5,6 +5,8 @@
 #include <stddef.h>
 #include <stdbool.h>
 
+#include "layer2/ham64.h"
+
 /* Common Link-layer Header */
 
 typedef enum {
@@ -16,14 +18,12 @@ typedef enum {
 typedef struct layer2_packet_header_s {
 	layer2_message_type_t msg_type; //!< message type
 	bool tx_request;                //!< transmission request (marks the end of the burst)
-	uint8_t src_addr_len;           //!< source address length (in 16-bit words)
-	uint8_t dst_addr_len;           //!< destination address length (in 16-bit words)
 
 	uint8_t tx_seq_nr;              //!< sequence number of this packet
 	uint8_t rx_seq_nr;              //!< sequence number expected next from he other side
 
-	uint8_t src_addr[8];            //!< source HAM-64 address
-	uint8_t dst_addr[8];            //!< destination HAM-64 address
+	ham64_t src_addr;               //!< source HAM-64 address
+	ham64_t dst_addr;               //!< destination HAM-64 address
 } layer2_packet_header_t;
 
 /*!\brief Encode a layer2 packet header to the transmitted form.