diff --git a/packages/crypto/src/constants.ts b/packages/crypto/src/constants.ts
index d3fe154111..d028d3523f 100644
--- a/packages/crypto/src/constants.ts
+++ b/packages/crypto/src/constants.ts
@@ -4,8 +4,8 @@ export enum KeyType {
     SECP256K1 = 1,
 }
 
-export enum KeySize {
-    SECRET_KEY = 32,
-    ED25519_PUBLIC_KEY = 32,
-    SECP256k1_PUBLIC_KEY = 64,
-}
\ No newline at end of file
+export const KeySize = {
+    SECRET_KEY: 32,
+    ED25519_PUBLIC_KEY: 32,
+    SECP256k1_PUBLIC_KEY: 64,
+};
diff --git a/packages/crypto/src/public_key.ts b/packages/crypto/src/public_key.ts
index 06984cf83c..5aaf8e457e 100644
--- a/packages/crypto/src/public_key.ts
+++ b/packages/crypto/src/public_key.ts
@@ -30,7 +30,7 @@ function resolveEnumKeyName(keyType: KeyType) {
             return 'ed25519Key';
         }
         case KeyType.SECP256K1: {
-            return 'secp256k1Key'
+            return 'secp256k1Key';
         }
         default: {
             throw Error(`unknown type ${keyType}`);
diff --git a/packages/keystores-browser/test/browser_keystore.test.ts b/packages/keystores-browser/test/browser_keystore.test.ts
index 3b20fb7636..5b5541bbde 100644
--- a/packages/keystores-browser/test/browser_keystore.test.ts
+++ b/packages/keystores-browser/test/browser_keystore.test.ts
@@ -15,7 +15,7 @@ describe('Browser keystore', () => {
 });
 
 describe('Browser multi keystore', () => {
-    let ctx: any = {};
+    const ctx: any = {};
 
     beforeAll(async () => {
         ctx.keyStore = new MultiContractBrowserLocalStorageKeyStore(LocalStorageMemory);
diff --git a/packages/transactions/src/signature.ts b/packages/transactions/src/signature.ts
index 573bdf2b47..e803450472 100644
--- a/packages/transactions/src/signature.ts
+++ b/packages/transactions/src/signature.ts
@@ -10,7 +10,7 @@ function resolveEnumKeyName(keyType: KeyType) {
             return 'ed25519Signature';
         }
         case KeyType.SECP256K1: {
-            return 'secp256k1Signature'
+            return 'secp256k1Signature';
         }
         default: {
             throw Error(`unknown type ${keyType}`);
diff --git a/packages/utils/test/rpc-errors.test.ts b/packages/utils/test/rpc-errors.test.ts
index 0f72a85469..6ed55094de 100644
--- a/packages/utils/test/rpc-errors.test.ts
+++ b/packages/utils/test/rpc-errors.test.ts
@@ -46,7 +46,7 @@ describe('rpc-errors', () => {
     });
 
     test('test ShardCongested error', async () => {
-        let rpc_error = {
+        const rpc_error = {
             TxExecutionError: {
                 InvalidTxError: {
                     ShardCongested: {
@@ -56,7 +56,7 @@ describe('rpc-errors', () => {
                 }
             }
         };
-        let error: any = parseRpcError(rpc_error);
+        const error: any = parseRpcError(rpc_error);
         expect(error.type === 'ShardCongested').toBe(true);
         expect(error.shard_id).toBe(2);
         expect(error.congestion_level).toBe(0.4);
@@ -66,7 +66,7 @@ describe('rpc-errors', () => {
     });
 
     test('test ShardStuck error', async () => {
-        let rpc_error = {
+        const rpc_error = {
             TxExecutionError: {
                 InvalidTxError: {
                     ShardStuck: {
@@ -76,7 +76,7 @@ describe('rpc-errors', () => {
                 }
             }
         };
-        let error: any = parseRpcError(rpc_error);
+        const error: any = parseRpcError(rpc_error);
         expect(error.type === 'ShardStuck').toBe(true);
         expect(error.shard_id).toBe(2);
         expect(error.missed_chunks).toBe(5);
@@ -86,7 +86,7 @@ describe('rpc-errors', () => {
     });
 
     test('test ReceiptSizeExceeded error', async () => {
-        let rpc_error = {
+        const rpc_error = {
             TxExecutionError: {
                 InvalidTxError: {
                     ReceiptValidationError: {
@@ -98,12 +98,12 @@ describe('rpc-errors', () => {
                 }
             }
         };
-        let error: any = parseRpcError(rpc_error);
+        const error: any = parseRpcError(rpc_error);
         expect(error.type === 'ReceiptSizeExceeded').toBe(true);
         expect(error.limit).toBe(100);
         expect(error.size).toBe(101);
         expect(formatError(error.type, error)).toBe(
-            '{\"type\":\"ReceiptSizeExceeded\",\"limit\":100,\"size\":101,\"kind\":{\"limit\":100,\"size\":101}}'
+            '{"type":"ReceiptSizeExceeded","limit":100,"size":101,"kind":{"limit":100,"size":101}}'
         );
     });