diff --git a/packages/protobuf/scripts/protobuf-patches/index.js b/packages/protobuf/scripts/protobuf-patches/index.js
index fb75d42578..225879c26a 100644
--- a/packages/protobuf/scripts/protobuf-patches/index.js
+++ b/packages/protobuf/scripts/protobuf-patches/index.js
@@ -2,6 +2,7 @@ const fs = require('fs');
 const path = require('path');
 
 const UINT_TYPE = 'UintType';
+const SINT_TYPE = 'SintType';
 const DeviceModelInternal = 'DeviceModelInternal';
 
 // type rule fixes, ideally it should not be here
@@ -130,7 +131,7 @@ const TYPE_PATCH = {
     'CardanoSignTxInit.ttl': UINT_TYPE,
     'CardanoSignTxInit.validity_interval_start': UINT_TYPE,
     'CardanoSignTxInit.total_collateral': UINT_TYPE,
-    'CardanoToken.mint_amount': 'number | string', // TODO: Sint64 support
+    'CardanoToken.mint_amount': SINT_TYPE,
     'CardanoNativeScript.invalid_before': UINT_TYPE,
     'CardanoNativeScript.invalid_hereafter': UINT_TYPE,
     'EosAsset.symbol': 'string',
@@ -313,4 +314,5 @@ module.exports = {
     DEFINITION_PATCH,
     SKIP,
     UINT_TYPE,
+    SINT_TYPE,
 };
diff --git a/packages/protobuf/scripts/protobuf-types.js b/packages/protobuf/scripts/protobuf-types.js
index 2b9d5b8b11..37f301a82e 100644
--- a/packages/protobuf/scripts/protobuf-types.js
+++ b/packages/protobuf/scripts/protobuf-types.js
@@ -2,7 +2,7 @@ const fs = require('fs');
 const path = require('path');
 
 const json = require('../messages.json');
-const { RULE_PATCH, TYPE_PATCH, DEFINITION_PATCH, SKIP, UINT_TYPE } = require('./protobuf-patches');
+const { RULE_PATCH, TYPE_PATCH, DEFINITION_PATCH, SKIP, UINT_TYPE, SINT_TYPE } = require('./protobuf-patches');
 
 const INDENT = ' '.repeat(4);
 
@@ -160,6 +160,8 @@ const lines = []; // string[]
 lines.push('// This file is auto generated from data/messages/message.json', '');
 lines.push('// custom type uint32/64 may be represented as string');
 lines.push(`export type ${UINT_TYPE} = string | number;`, '');
+lines.push('// custom type sint32/64');
+lines.push(`export type ${SINT_TYPE} = string | number;`, '');
 lines.push(
     `export enum DeviceModelInternal {
     T1B1 = 'T1B1',
diff --git a/packages/protobuf/src/messages-schema.ts b/packages/protobuf/src/messages-schema.ts
index 8cd90aad93..e1c088e2ee 100644
--- a/packages/protobuf/src/messages-schema.ts
+++ b/packages/protobuf/src/messages-schema.ts
@@ -871,7 +871,7 @@ export type CardanoToken = Static<typeof CardanoToken>;
 export const CardanoToken = Type.Object({
     asset_name_bytes: Type.String(),
     amount: Type.Optional(Type.Uint()),
-    mint_amount: Type.Optional(Type.Uint()),
+    mint_amount: Type.Optional(Type.Uint({ allowNegative: true })),
 });
 
 export type CardanoTxInlineDatumChunk = Static<typeof CardanoTxInlineDatumChunk>;
@@ -2279,7 +2279,7 @@ export const StellarSignTx = Type.Object({
     timebounds_end: Type.Number(),
     memo_type: EnumStellarMemoType,
     memo_text: Type.Optional(Type.String()),
-    memo_id: Type.Optional(Type.String()),
+    memo_id: Type.Optional(Type.Uint()),
     memo_hash: Type.Optional(Type.Union([Type.Buffer(), Type.String()])),
     num_operations: Type.Number(),
 });
diff --git a/packages/protobuf/src/messages.ts b/packages/protobuf/src/messages.ts
index 7315d96395..d1cde35048 100644
--- a/packages/protobuf/src/messages.ts
+++ b/packages/protobuf/src/messages.ts
@@ -3,6 +3,9 @@
 // custom type uint32/64 may be represented as string
 export type UintType = string | number;
 
+// custom type sint32/64
+export type SintType = string | number;
+
 export enum DeviceModelInternal {
     T1B1 = 'T1B1',
     T2T1 = 'T2T1',
@@ -783,7 +786,7 @@ export type CardanoAssetGroup = {
 export type CardanoToken = {
     asset_name_bytes: string;
     amount?: UintType;
-    mint_amount?: UintType;
+    mint_amount?: SintType;
 };
 
 // CardanoTxInlineDatumChunk
@@ -2078,7 +2081,7 @@ export type StellarSignTx = {
     timebounds_end: number;
     memo_type: StellarMemoType;
     memo_text?: string;
-    memo_id?: string;
+    memo_id?: UintType;
     memo_hash?: Buffer | string;
     num_operations: number;
 };
diff --git a/packages/schema-utils/src/codegen.ts b/packages/schema-utils/src/codegen.ts
index fddbb0dc03..d378d9284d 100644
--- a/packages/schema-utils/src/codegen.ts
+++ b/packages/schema-utils/src/codegen.ts
@@ -13,6 +13,7 @@ export function generate(code: string) {
         ArrayBuffer: 'Type.ArrayBuffer()',
         Buffer: 'Type.Buffer()',
         UintType: 'Type.Uint()',
+        SintType: 'Type.Uint({ allowNegative: true })',
     };
     const customTypePlaceholder = Object.keys(customTypesMapping).map(t => `type ${t} = any;`);
     // Run generator
diff --git a/packages/schema-utils/tests/__snapshots__/codegen.test.ts.snap b/packages/schema-utils/tests/__snapshots__/codegen.test.ts.snap
index 0c17301cc2..cca25bfebd 100644
--- a/packages/schema-utils/tests/__snapshots__/codegen.test.ts.snap
+++ b/packages/schema-utils/tests/__snapshots__/codegen.test.ts.snap
@@ -5,6 +5,12 @@ exports[`codegen should generate code for protobuf messages example 1`] = `
 import { Type, Static } from '@trezor/schema-utils';
 
 
+export type Type.Uint() = Static<typeof Type.Uint()>
+export const Type.Uint() = Type.Union([
+Type.String(),
+Type.Number()
+])
+
 export enum DeviceModelInternal { T1B1 = 'T1B1', T2T1 = 'T2T1', T2B1 = 'T2B1' }
 
 export type EnumDeviceModelInternal = Static<typeof EnumDeviceModelInternal>