diff --git a/__tests__/utils/__snapshots__/ellipticalCurve.test.ts.snap b/__tests__/utils/__snapshots__/ellipticalCurve.test.ts.snap
index c540f5f84..74ce57b39 100644
--- a/__tests__/utils/__snapshots__/ellipticalCurve.test.ts.snap
+++ b/__tests__/utils/__snapshots__/ellipticalCurve.test.ts.snap
@@ -1,3 +1,5 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
 exports[`pedersen() 1`] = `"0x5ed2703dfdb505c587700ce2ebfcab5b3515cd7e6114817e6026ec9d4b364ca"`;
+
+exports[`pedersen() with 0 1`] = `"0x1a5c561f97b52c17a19f34c4499a745cd4e8412e29e4ed5e91e4481c7d53935"`;
diff --git a/__tests__/utils/ellipticalCurve.test.ts b/__tests__/utils/ellipticalCurve.test.ts
index 21ed1339c..2bba8d4ec 100644
--- a/__tests__/utils/ellipticalCurve.test.ts
+++ b/__tests__/utils/ellipticalCurve.test.ts
@@ -25,6 +25,11 @@ test('pedersen()', () => {
   expect(own).toMatchSnapshot();
 });
 
+test('pedersen() with 0', () => {
+  const own = pedersen(['0x12773', '0x0']);
+  expect(own).toMatchSnapshot();
+});
+
 test('computeHashOnElements()', () => {
   const array = ['1', '2', '3', '4'];
   expect(computeHashOnElements(array)).toBe(
diff --git a/src/account/session.ts b/src/account/session.ts
index 09e22be0e..2e1b2bfca 100644
--- a/src/account/session.ts
+++ b/src/account/session.ts
@@ -1,3 +1,5 @@
+import assert from 'minimalistic-assert';
+
 import { ZERO } from '../constants';
 import { ProviderInterface, ProviderOptions } from '../provider';
 import { SignerInterface } from '../signer';
@@ -12,8 +14,9 @@ import {
   KeyPair,
 } from '../types';
 import { feeTransactionVersion, transactionVersion } from '../utils/hash';
+import { MerkleTree } from '../utils/merkle';
 import { BigNumberish, toBN } from '../utils/number';
-import type { SignedSession } from '../utils/session';
+import { SignedSession, createMerkleTreeForPolicies } from '../utils/session';
 import { compileCalldata, estimatedFeeToMaxFee } from '../utils/stark';
 import { fromCallsToExecuteCalldataWithNonce } from '../utils/transaction';
 import { Account } from './default';
@@ -23,6 +26,8 @@ const SESSION_PLUGIN_CLASS_HASH =
   '0x6a184757e350de1fe3a544037efbef6434724980a572f294c90555dadc20052';
 
 export class SessionAccount extends Account implements AccountInterface {
+  public merkleTree: MerkleTree;
+
   constructor(
     providerOrOptions: ProviderOptions | ProviderInterface,
     address: string,
@@ -30,6 +35,8 @@ export class SessionAccount extends Account implements AccountInterface {
     public signedSession: SignedSession
   ) {
     super(providerOrOptions, address, keyPairOrSigner);
+    this.merkleTree = createMerkleTreeForPolicies(signedSession.policies);
+    assert(signedSession.root === this.merkleTree.root, 'Invalid session');
   }
 
   private async sessionToCall(session: SignedSession): Promise<Call> {
diff --git a/src/utils/hash.ts b/src/utils/hash.ts
index 3c6041371..c9f6dab69 100644
--- a/src/utils/hash.ts
+++ b/src/utils/hash.ts
@@ -62,13 +62,15 @@ export function pedersen(input: [BigNumberish, BigNumberish]) {
   for (let i = 0; i < input.length; i += 1) {
     let x = toBN(input[i]);
     assert(x.gte(ZERO) && x.lt(toBN(addHexPrefix(FIELD_PRIME))), `Invalid input: ${input[i]}`);
-    for (let j = 0; j < 252; j += 1) {
-      const pt = constantPoints[2 + i * 252 + j];
-      assert(!point.getX().eq(pt.getX()));
-      if (x.and(ONE).toNumber() !== 0) {
-        point = point.add(pt);
+    if (!x.isZero()) {
+      for (let j = 0; j < 252; j += 1) {
+        const pt = constantPoints[2 + i * 252 + j];
+        assert(!point.getX().eq(pt.getX()));
+        if (x.and(ONE).toNumber() !== 0) {
+          point = point.add(pt);
+        }
+        x = x.shrn(1);
       }
-      x = x.shrn(1);
     }
   }
   return addHexPrefix(point.getX().toString(16));
diff --git a/src/utils/session.ts b/src/utils/session.ts
index c756a8983..baebc22ce 100644
--- a/src/utils/session.ts
+++ b/src/utils/session.ts
@@ -9,16 +9,13 @@ interface Policy {
   selector: string;
 }
 
-interface BaseSession {
+export interface RequestSession {
   key: string;
   expires: number;
-}
-
-export interface RequestSession extends BaseSession {
   policies: Policy[];
 }
 
-export interface PreparedSession extends BaseSession {
+export interface PreparedSession extends RequestSession {
   root: string;
 }
 
@@ -30,10 +27,13 @@ function preparePolicy({ contractAddress, selector }: Policy): string {
   return pedersen([contractAddress, prepareSelector(selector)]);
 }
 
+export function createMerkleTreeForPolicies(policies: Policy[]): MerkleTree {
+  return new MerkleTree(policies.map(preparePolicy));
+}
+
 export function prepareSession(session: RequestSession): PreparedSession {
-  const { policies, ...rest } = session;
-  const { root } = new MerkleTree(policies.map(preparePolicy));
-  return { ...rest, root };
+  const { root } = createMerkleTreeForPolicies(session.policies);
+  return { ...session, root };
 }
 
 export async function createSession(
@@ -41,7 +41,7 @@ export async function createSession(
   account: AccountInterface,
   domain: StarkNetDomain = {}
 ): Promise<SignedSession> {
-  const { key, expires, root } = prepareSession(session);
+  const { expires, key, policies, root } = prepareSession(session);
   const signature = await account.signMessage({
     primaryType: 'Session',
     types: {
@@ -69,6 +69,7 @@ export async function createSession(
   });
   return {
     key,
+    policies,
     expires,
     root,
     signature,