diff --git a/mesh/net-keys.c b/mesh/net-keys.c
index 25f4cae..5be7e0b 100644
--- a/mesh/net-keys.c
+++ b/mesh/net-keys.c
@@ -209,12 +209,6 @@ static void decrypt_net_pkt(void *a, void *b)
 uint32_t net_key_decrypt(uint32_t iv_index, const uint8_t *pkt, size_t len,
 					uint8_t **plain, size_t *plain_len)
 {
-	bool iv_flag = !!(iv_index & 1);
-	bool iv_pkt = !!(pkt[0] & 0x80);
-
-	if (iv_pkt != iv_flag)
-		iv_index--;
-
 	/* If we already successfully decrypted this packet, use cached data */
 	if (cache_id && cache_len == len && !memcmp(pkt, cache_pkt, len)) {
 		/* IV Index must match what was used to decrypt */
diff --git a/mesh/net.c b/mesh/net.c
index a597b87..a5693f1 100644
--- a/mesh/net.c
+++ b/mesh/net.c
@@ -2489,8 +2489,13 @@ static void net_rx(void *net_ptr, void *user_data)
 	size_t out_size;
 	uint32_t key_id;
 	int8_t rssi = 0;
+	bool ivi_net = !!(net->iv_index & 1);
+	bool ivi_pkt = !!(data->data[0] & 0x80);
 
-	key_id = net_key_decrypt(net->iv_index, data->data, data->len,
+	/* if IVI flag differs, use previous IV Index */
+	uint32_t iv_index = net->iv_index - (ivi_pkt ^ ivi_net);
+
+	key_id = net_key_decrypt(iv_index, data->data, data->len,
 							&out, &out_size);
 
 	if (!key_id)
@@ -2504,16 +2509,10 @@ static void net_rx(void *net_ptr, void *user_data)
 		rssi = data->info->rssi;
 	}
 
-	relay_advice = packet_received(net, key_id, net->iv_index,
+	relay_advice = packet_received(net, key_id, iv_index,
 							out, out_size, rssi);
 	if (relay_advice > data->relay_advice) {
-		bool iv_flag = !!(net->iv_index & 1);
-		bool iv_pkt = !!(data->data[0] & 0x80);
-
-		data->iv_index = net->iv_index;
-		if (iv_pkt != iv_flag)
-			data->iv_index--;
-
+		data->iv_index = iv_index;
 		data->relay_advice = relay_advice;
 		data->key_id = key_id;
 		data->net = net;