diff --git a/common/protob/messages-bitcoin.proto b/common/protob/messages-bitcoin.proto
index 0b8263608..fa36190c0 100644
--- a/common/protob/messages-bitcoin.proto
+++ b/common/protob/messages-bitcoin.proto
@@ -329,7 +329,7 @@ message TxAck {
             // optional uint32 block_height_bip115 = 9;     // BIP-115 support dropped
             optional bytes orig_hash = 10;                  // tx_hash of the original transaction where this output was present (used when creating a replacement transaction)
             optional uint32 orig_index = 11;                // index of the output in the original transaction (used when creating a replacement transaction)
-            optional uint32 payment_req_index = 12;         // index of the PaymentRequest containing this output
+            optional uint32 payment_req_index = 12 [(experimental)=true]; // index of the PaymentRequest containing this output
         }
     }
 }
@@ -373,7 +373,7 @@ message TxOutput {
     reserved 7, 8, 9;                               // fields which are in use, or have been in the past, in TxOutputType
     optional bytes orig_hash = 10;                  // tx_hash of the original transaction where this output was present (used when creating a replacement transaction)
     optional uint32 orig_index = 11;                // index of the output in the original transaction (used when creating a replacement transaction)
-    optional uint32 payment_req_index = 12;         // index of the PaymentRequest containing this output
+    optional uint32 payment_req_index = 12 [(experimental)=true]; // index of the PaymentRequest containing this output
 }
 
 /** Data type for metadata about previous transaction which contains the UTXO being spent.
@@ -423,6 +423,8 @@ message PrevOutput {
  * @next TxRequest
  */
 message TxAckPaymentRequest {
+    option (unstable) = true;
+
     optional bytes nonce = 1;              // the nonce used in the signature computation
     required string recipient_name = 2;    // merchant's name or coordinator's name in case of CoinJoin
     repeated PaymentRequestMemo memos = 3; // any memos that were signed as part of the request
diff --git a/common/protob/messages-management.proto b/common/protob/messages-management.proto
index d4ba2432a..aa15c8f13 100644
--- a/common/protob/messages-management.proto
+++ b/common/protob/messages-management.proto
@@ -428,6 +428,7 @@ message RebootToBootloader {
  * @next Nonce
  */
 message GetNonce {
+    option (unstable) = true;
 }
 
 /**
@@ -435,5 +436,7 @@ message GetNonce {
  * @end
  */
 message Nonce {
+    option (unstable) = true;
+
     required bytes nonce = 1; // a 32-byte random value generated by Trezor
 }