diff --git a/firmware/ethereum.c b/firmware/ethereum.c
index a7342391ad..8d6c78ec11 100644
--- a/firmware/ethereum.c
+++ b/firmware/ethereum.c
@@ -438,6 +438,8 @@ void ethereum_signing_init(EthereumSignTx *msg, const HDNode *node)
 		msg->to.size = 0;
 	if (!msg->has_nonce)
 		msg->nonce.size = 0;
+	if (!msg->has_prefix)
+		msg->prefix.size = 0;
 
 	/* eip-155 chain id */
 	if (msg->has_chain_id) {
@@ -512,6 +514,9 @@ void ethereum_signing_init(EthereumSignTx *msg, const HDNode *node)
 
 	layoutProgress("Signing", 0);
 
+	if (msg->has_prefix) {
+		rlp_length += rlp_calculate_length(msg->prefix.size, msg->prefix.bytes[0]);
+	}
 	rlp_length += rlp_calculate_length(msg->nonce.size, msg->nonce.bytes[0]);
 	rlp_length += rlp_calculate_length(msg->gas_price.size, msg->gas_price.bytes[0]);
 	rlp_length += rlp_calculate_length(msg->gas_limit.size, msg->gas_limit.bytes[0]);
@@ -529,6 +534,9 @@ void ethereum_signing_init(EthereumSignTx *msg, const HDNode *node)
 
 	layoutProgress("Signing", 100);
 
+	if (msg->has_prefix) {
+		hash_rlp_field(msg->prefix.bytes, msg->prefix.size);
+	}
 	hash_rlp_field(msg->nonce.bytes, msg->nonce.size);
 	hash_rlp_field(msg->gas_price.bytes, msg->gas_price.size);
 	hash_rlp_field(msg->gas_limit.bytes, msg->gas_limit.size);
diff --git a/firmware/protob/messages.options b/firmware/protob/messages.options
index 7138c65978..c538e5e99d 100644
--- a/firmware/protob/messages.options
+++ b/firmware/protob/messages.options
@@ -100,6 +100,7 @@ EthereumSignTx.gas_limit		max_size:32
 EthereumSignTx.to			max_size:20
 EthereumSignTx.value			max_size:32
 EthereumSignTx.data_initial_chunk	max_size:1024
+EthereumSignTx.prefix			max_size:32
 
 EthereumTxRequest.signature_r		max_size:32
 EthereumTxRequest.signature_s		max_size:32
diff --git a/firmware/protob/messages.pb.c b/firmware/protob/messages.pb.c
index b2421129d4..5a55dbeb03 100644
--- a/firmware/protob/messages.pb.c
+++ b/firmware/protob/messages.pb.c
@@ -325,7 +325,7 @@ const pb_field_t TxAck_fields[2] = {
     PB_LAST_FIELD
 };
 
-const pb_field_t EthereumSignTx_fields[10] = {
+const pb_field_t EthereumSignTx_fields[11] = {
     PB_FIELD2(  1, UINT32  , REPEATED, STATIC  , FIRST, EthereumSignTx, address_n, address_n, 0),
     PB_FIELD2(  2, BYTES   , OPTIONAL, STATIC  , OTHER, EthereumSignTx, nonce, address_n, 0),
     PB_FIELD2(  3, BYTES   , OPTIONAL, STATIC  , OTHER, EthereumSignTx, gas_price, nonce, 0),
@@ -335,6 +335,7 @@ const pb_field_t EthereumSignTx_fields[10] = {
     PB_FIELD2(  7, BYTES   , OPTIONAL, STATIC  , OTHER, EthereumSignTx, data_initial_chunk, value, 0),
     PB_FIELD2(  8, UINT32  , OPTIONAL, STATIC  , OTHER, EthereumSignTx, data_length, data_initial_chunk, 0),
     PB_FIELD2(  9, UINT32  , OPTIONAL, STATIC  , OTHER, EthereumSignTx, chain_id, data_length, 0),
+    PB_FIELD2( 10, BYTES   , OPTIONAL, STATIC  , OTHER, EthereumSignTx, prefix, chain_id, 0),
     PB_LAST_FIELD
 };
 
diff --git a/firmware/protob/messages.pb.h b/firmware/protob/messages.pb.h
index 0dad8391fc..d8470eb997 100644
--- a/firmware/protob/messages.pb.h
+++ b/firmware/protob/messages.pb.h
@@ -444,6 +444,11 @@ typedef struct {
     uint8_t bytes[1024];
 } EthereumSignTx_data_initial_chunk_t;
 
+typedef struct {
+    size_t size;
+    uint8_t bytes[32];
+} EthereumSignTx_prefix_t;
+
 typedef struct _EthereumSignTx {
     size_t address_n_count;
     uint32_t address_n[8];
@@ -463,6 +468,8 @@ typedef struct _EthereumSignTx {
     uint32_t data_length;
     bool has_chain_id;
     uint32_t chain_id;
+    bool has_prefix;
+    EthereumSignTx_prefix_t prefix;
 } EthereumSignTx;
 
 typedef struct {
@@ -872,7 +879,7 @@ extern const uint32_t SignTx_lock_time_default;
 #define SignTx_init_default                      {0, 0, false, "Bitcoin", false, 1u, false, 0u}
 #define TxRequest_init_default                   {false, (RequestType)0, false, TxRequestDetailsType_init_default, false, TxRequestSerializedType_init_default}
 #define TxAck_init_default                       {false, TransactionType_init_default}
-#define EthereumSignTx_init_default              {0, {0, 0, 0, 0, 0, 0, 0, 0}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, 0, false, 0}
+#define EthereumSignTx_init_default              {0, {0, 0, 0, 0, 0, 0, 0, 0}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, 0, false, 0, false, {0, {0}}}
 #define EthereumTxRequest_init_default           {false, 0, false, 0, false, {0, {0}}, false, {0, {0}}}
 #define EthereumTxAck_init_default               {false, {0, {0}}}
 #define SignIdentity_init_default                {false, IdentityType_init_default, false, {0, {0}}, false, "", false, ""}
@@ -936,7 +943,7 @@ extern const uint32_t SignTx_lock_time_default;
 #define SignTx_init_zero                         {0, 0, false, "", false, 0, false, 0}
 #define TxRequest_init_zero                      {false, (RequestType)0, false, TxRequestDetailsType_init_zero, false, TxRequestSerializedType_init_zero}
 #define TxAck_init_zero                          {false, TransactionType_init_zero}
-#define EthereumSignTx_init_zero                 {0, {0, 0, 0, 0, 0, 0, 0, 0}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, 0, false, 0}
+#define EthereumSignTx_init_zero                 {0, {0, 0, 0, 0, 0, 0, 0, 0}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, {0, {0}}, false, 0, false, 0, false, {0, {0}}}
 #define EthereumTxRequest_init_zero              {false, 0, false, 0, false, {0, {0}}, false, {0, {0}}}
 #define EthereumTxAck_init_zero                  {false, {0, {0}}}
 #define SignIdentity_init_zero                   {false, IdentityType_init_zero, false, {0, {0}}, false, "", false, ""}
@@ -1025,6 +1032,7 @@ extern const uint32_t SignTx_lock_time_default;
 #define EthereumSignTx_data_initial_chunk_tag    7
 #define EthereumSignTx_data_length_tag           8
 #define EthereumSignTx_chain_id_tag              9
+#define EthereumSignTx_prefix_tag                10
 #define EthereumTxAck_data_chunk_tag             1
 #define EthereumTxRequest_data_length_tag        1
 #define EthereumTxRequest_signature_v_tag        2
@@ -1173,7 +1181,7 @@ extern const pb_field_t TxSize_fields[2];
 extern const pb_field_t SignTx_fields[6];
 extern const pb_field_t TxRequest_fields[4];
 extern const pb_field_t TxAck_fields[2];
-extern const pb_field_t EthereumSignTx_fields[10];
+extern const pb_field_t EthereumSignTx_fields[11];
 extern const pb_field_t EthereumTxRequest_fields[5];
 extern const pb_field_t EthereumTxAck_fields[2];
 extern const pb_field_t SignIdentity_fields[5];
@@ -1239,7 +1247,7 @@ extern const pb_field_t DebugLinkFlashErase_fields[2];
 #define SignTx_size                              43
 #define TxRequest_size                           (18 + TxRequestDetailsType_size + TxRequestSerializedType_size)
 #define TxAck_size                               (6 + TransactionType_size)
-#define EthereumSignTx_size                      1245
+#define EthereumSignTx_size                      1279
 #define EthereumTxRequest_size                   80
 #define EthereumTxAck_size                       1027
 #define SignIdentity_size                        (558 + IdentityType_size)
diff --git a/vendor/trezor-common b/vendor/trezor-common
index dd1f7a2b0b..78da723c06 160000
--- a/vendor/trezor-common
+++ b/vendor/trezor-common
@@ -1 +1 @@
-Subproject commit dd1f7a2b0b44793734e286239f64ddb3d816058d
+Subproject commit 78da723c063ae0aa76e06a517fe48d0013928cc4