diff --git a/legacy/firmware/ethereum_definitions.c b/legacy/firmware/ethereum_definitions.c
index 7bdc155869..4ffc3de388 100644
--- a/legacy/firmware/ethereum_definitions.c
+++ b/legacy/firmware/ethereum_definitions.c
@@ -242,7 +242,8 @@ bool _get_EthereumNetworkInfo(
         // chain_id mismatch - error and reset definition
         fsm_sendFailure(FailureType_Failure_DataError,
                         _("Invalid network definition - chain IDs not equal."));
-        _set_EthereumNetworkInfo_to_builtin(ref_chain_id, network);
+        _set_EthereumNetworkInfo_to_builtin(CHAIN_ID_UNKNOWN, network);
+        return false;
       } else {
         // chain_id does match the reference one (if provided) so prepend one
         // space character to symbol, terminate it (encoded definitions does not
@@ -251,15 +252,14 @@ bool _get_EthereumNetworkInfo(
                 sizeof(network->shortcut) - 2);
         network->shortcut[0] = ' ';
         network->shortcut[sizeof(network->shortcut) - 1] = 0;
-        return true;
       }
     } else {
       // decoding failed - reset network definition
-      _set_EthereumNetworkInfo_to_builtin(ref_chain_id, network);
+      _set_EthereumNetworkInfo_to_builtin(CHAIN_ID_UNKNOWN, network);
     }
   }
 
-  return network->chain_id == CHAIN_ID_UNKNOWN ? false : true;
+  return true;
 }
 
 void _get_EthereumTokenInfo(
@@ -322,7 +322,13 @@ const EthereumDefinitions *get_EthereumDefinitions(
     const uint64_t ref_chain_id, const char *ref_address) {
   static EthereumDefinitions defs;
 
-  if (_get_EthereumNetworkInfo(encoded_network, ref_chain_id, &defs.network)) {
+  if (!_get_EthereumNetworkInfo(encoded_network, ref_chain_id, &defs.network)) {
+    // error while decoding - chain IDs mismatch
+    return NULL;
+  }
+
+  if (strncmp(defs.network.shortcut, UNKNOWN_NETWORK_SHORTCUT,
+              sizeof(defs.network.shortcut)) != 0) {
     // we have found network definition, we can try to load token definition
     _get_EthereumTokenInfo(encoded_token, ref_chain_id, ref_address,
                            &defs.token);
diff --git a/legacy/firmware/fsm_msg_ethereum.h b/legacy/firmware/fsm_msg_ethereum.h
index 5df5b5ae5f..8914a6f400 100644
--- a/legacy/firmware/fsm_msg_ethereum.h
+++ b/legacy/firmware/fsm_msg_ethereum.h
@@ -47,6 +47,10 @@ void fsm_msgEthereumGetPublicKey(const EthereumGetPublicKey *msg) {
 
   const EthereumDefinitions *defs =
       get_EthereumDefinitions(encoded_network, NULL, CHAIN_ID_UNKNOWN, NULL);
+  if (!defs) {
+    layoutHome();
+    return;
+  }
 
   // we use Bitcoin-like format for ETH
   const CoinInfo *coin = fsm_getCoin(true, "Bitcoin");
@@ -119,8 +123,8 @@ void fsm_msgEthereumSignTx(const EthereumSignTx *msg) {
       get_EthereumDefinitions(encoded_network, encoded_token, msg->chain_id,
                               msg->has_to ? msg->to : NULL);
 
-  if (!fsm_ethereumCheckPath(msg->address_n_count, msg->address_n, false,
-                             defs)) {
+  if (!defs || !fsm_ethereumCheckPath(msg->address_n_count, msg->address_n,
+                                      false, defs)) {
     layoutHome();
     return;
   }
@@ -155,8 +159,8 @@ void fsm_msgEthereumSignTxEIP1559(const EthereumSignTxEIP1559 *msg) {
       get_EthereumDefinitions(encoded_network, encoded_token, msg->chain_id,
                               msg->has_to ? msg->to : NULL);
 
-  if (!fsm_ethereumCheckPath(msg->address_n_count, msg->address_n, false,
-                             defs)) {
+  if (!defs || !fsm_ethereumCheckPath(msg->address_n_count, msg->address_n,
+                                      false, defs)) {
     layoutHome();
     return;
   }
@@ -190,8 +194,8 @@ void fsm_msgEthereumGetAddress(const EthereumGetAddress *msg) {
   const EthereumDefinitions *defs =
       get_EthereumDefinitions(encoded_network, NULL, CHAIN_ID_UNKNOWN, NULL);
 
-  if (!fsm_ethereumCheckPath(msg->address_n_count, msg->address_n, false,
-                             defs)) {
+  if (!defs || !fsm_ethereumCheckPath(msg->address_n_count, msg->address_n,
+                                      false, defs)) {
     layoutHome();
     return;
   }
@@ -263,8 +267,8 @@ void fsm_msgEthereumSignMessage(const EthereumSignMessage *msg) {
   const EthereumDefinitions *defs =
       get_EthereumDefinitions(encoded_network, NULL, CHAIN_ID_UNKNOWN, NULL);
 
-  if (!fsm_ethereumCheckPath(msg->address_n_count, msg->address_n, false,
-                             defs)) {
+  if (!defs || !fsm_ethereumCheckPath(msg->address_n_count, msg->address_n,
+                                      false, defs)) {
     layoutHome();
     return;
   }
@@ -359,8 +363,8 @@ void fsm_msgEthereumSignTypedHash(const EthereumSignTypedHash *msg) {
   const EthereumDefinitions *defs =
       get_EthereumDefinitions(encoded_network, NULL, CHAIN_ID_UNKNOWN, NULL);
 
-  if (!fsm_ethereumCheckPath(msg->address_n_count, msg->address_n, false,
-                             defs)) {
+  if (!defs || !fsm_ethereumCheckPath(msg->address_n_count, msg->address_n,
+                                      false, defs)) {
     layoutHome();
     return;
   }