diff --git a/lib/client.js b/lib/client.js
index 85b24380..e7a57163 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -988,6 +988,17 @@ module.exports = (issuer, aadIssValidation = false) => class Client extends Base
     if (tokenset.id_token) {
       await this.decryptIdToken(tokenset);
       await this.validateIdToken(tokenset, null, 'token', null);
+
+      if (refreshToken instanceof TokenSet && refreshToken.id_token) {
+        const expectedSub = refreshToken.claims().sub;
+        const actualSub = tokenset.claims().sub;
+        if (actualSub !== expectedSub) {
+          throw new RPError({
+            printf: ['sub mismatch, expected %s, got: %s', expectedSub, actualSub],
+            jwt: tokenset.id_token,
+          });
+        }
+      }
     }
 
     return tokenset;
diff --git a/test/client/client_instance.test.js b/test/client/client_instance.test.js
index 719a8239..db7f0c56 100644
--- a/test/client/client_instance.test.js
+++ b/test/client/client_instance.test.js
@@ -873,11 +873,13 @@ describe('Client', () => {
   describe('#refresh', function () {
     before(function () {
       const issuer = new Issuer({
+        issuer: 'https://op.example.com',
         token_endpoint: 'https://op.example.com/token',
       });
       this.client = new issuer.Client({
         client_id: 'identifier',
         client_secret: 'secure',
+        id_token_signed_response_alg: 'HS256',
       });
     });
 
@@ -931,6 +933,65 @@ describe('Client', () => {
         });
     });
 
+    it('passes ID Token validations when ID Token is returned', function () {
+      nock('https://op.example.com')
+        .post('/token') // to make sure filteringRequestBody works
+        .reply(200, {
+          access_token: 'present',
+          refresh_token: 'refreshValue',
+          id_token: jose.JWT.sign({
+            sub: 'foo',
+          }, this.client.client_secret, {
+            issuer: this.client.issuer.issuer,
+            audience: this.client.client_id,
+            expiresIn: '5m',
+          }),
+        });
+
+      return this.client.refresh(new TokenSet({
+        access_token: 'present',
+        refresh_token: 'refreshValue',
+        id_token: jose.JWT.sign({
+          sub: 'foo',
+        }, this.client.client_secret, {
+          issuer: this.client.issuer.issuer,
+          audience: this.client.client_id,
+          expiresIn: '6m',
+        }),
+      }));
+    });
+
+    it('rejects when returned ID Token sub does not match the one passed in', function () {
+      nock('https://op.example.com')
+        .post('/token') // to make sure filteringRequestBody works
+        .reply(200, {
+          access_token: 'present',
+          refresh_token: 'refreshValue',
+          id_token: jose.JWT.sign({
+            sub: 'bar',
+          }, this.client.client_secret, {
+            issuer: this.client.issuer.issuer,
+            audience: this.client.client_id,
+            expiresIn: '5m',
+          }),
+        });
+
+      return this.client.refresh(new TokenSet({
+        access_token: 'present',
+        refresh_token: 'refreshValue',
+        id_token: jose.JWT.sign({
+          sub: 'foo',
+        }, this.client.client_secret, {
+          issuer: this.client.issuer.issuer,
+          audience: this.client.client_id,
+          expiresIn: '5m',
+        }),
+      }))
+        .then(fail, (error) => {
+          expect(error).to.have.property('message', 'sub mismatch, expected foo, got: bar');
+        });
+    });
+
     it('rejects when passed a TokenSet not containing refresh_token', function () {
       return this.client.refresh(new TokenSet({
         access_token: 'present',