diff --git a/src/Grant/AuthCodeGrant.php b/src/Grant/AuthCodeGrant.php
index 14aac2a3..6a2ee795 100644
--- a/src/Grant/AuthCodeGrant.php
+++ b/src/Grant/AuthCodeGrant.php
@@ -28,11 +28,6 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
      */
     private $authCodeTTL;
 
-    /**
-     * @var bool
-     */
-    private $enableCodeExchangeProof = false;
-
     /**
      * @param AuthCodeRepositoryInterface     $authCodeRepository
      * @param RefreshTokenRepositoryInterface $refreshTokenRepository
@@ -49,11 +44,6 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
         $this->refreshTokenTTL = new \DateInterval('P1M');
     }
 
-    public function enableCodeExchangeProof()
-    {
-        $this->enableCodeExchangeProof = true;
-    }
-
     /**
      * Respond to an access token request.
      *
@@ -81,6 +71,7 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
         // Validate the authorization code
         try {
             $authCodePayload = json_decode($this->decrypt($encryptedAuthCode));
+	    
             if (time() > $authCodePayload->expire_time) {
                 throw OAuthServerException::invalidRequest('code', 'Authorization code has expired');
             }
@@ -104,6 +95,7 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
             }
 
             $scopes = [];
+
             foreach ($authCodePayload->scopes as $scopeId) {
                 $scope = $this->scopeRepository->getScopeEntityByIdentifier($scopeId);
 
@@ -127,9 +119,11 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
             throw OAuthServerException::invalidRequest('code', 'Cannot decrypt the authorization code');
         }
 
+
         // Validate code challenge
-        if ($this->enableCodeExchangeProof === true) {
-            $codeVerifier = $this->getRequestParameter('code_verifier', $request, null);
+        if (!empty($authCodePayload->code_challenge)) {
+	    $codeVerifier = $this->getRequestParameter('code_verifier', $request, null);
+
             if ($codeVerifier === null) {
                 throw OAuthServerException::invalidRequest('code_verifier');
             }
diff --git a/tests/Grant/AuthCodeGrantTest.php b/tests/Grant/AuthCodeGrantTest.php
index 6bc2dd7a..5ca3c8f1 100644
--- a/tests/Grant/AuthCodeGrantTest.php
+++ b/tests/Grant/AuthCodeGrantTest.php
@@ -173,7 +173,7 @@ class AuthCodeGrantTest extends TestCase
             $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
             new \DateInterval('PT10M')
         );
-        $grant->enableCodeExchangeProof();
+
         $grant->setClientRepository($clientRepositoryMock);
         $grant->setScopeRepository($scopeRepositoryMock);
         $grant->setDefaultScope(self::DEFAULT_SCOPE);
@@ -249,7 +249,7 @@ class AuthCodeGrantTest extends TestCase
             $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
             new \DateInterval('PT10M')
         );
-        $grant->enableCodeExchangeProof();
+
         $grant->setClientRepository($clientRepositoryMock);
 
         $request = new ServerRequest(
@@ -286,7 +286,7 @@ class AuthCodeGrantTest extends TestCase
             $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
             new \DateInterval('PT10M')
         );
-        $grant->enableCodeExchangeProof();
+
         $grant->setClientRepository($clientRepositoryMock);
 
         $request = new ServerRequest(
@@ -464,7 +464,7 @@ class AuthCodeGrantTest extends TestCase
             $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
             new \DateInterval('PT10M')
         );
-        $grant->enableCodeExchangeProof();
+
         $grant->setClientRepository($clientRepositoryMock);
         $grant->setScopeRepository($scopeRepositoryMock);
         $grant->setDefaultScope(self::DEFAULT_SCOPE);
@@ -629,7 +629,7 @@ class AuthCodeGrantTest extends TestCase
             $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
             new \DateInterval('PT10M')
         );
-        $grant->enableCodeExchangeProof();
+	
         $grant->setClientRepository($clientRepositoryMock);
         $grant->setScopeRepository($scopeRepositoryMock);
         $grant->setAccessTokenRepository($accessTokenRepositoryMock);
@@ -701,7 +701,7 @@ class AuthCodeGrantTest extends TestCase
             $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
             new \DateInterval('PT10M')
         );
-        $grant->enableCodeExchangeProof();
+
         $grant->setClientRepository($clientRepositoryMock);
         $grant->setScopeRepository($scopeRepositoryMock);
         $grant->setAccessTokenRepository($accessTokenRepositoryMock);
@@ -1145,7 +1145,7 @@ class AuthCodeGrantTest extends TestCase
             $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
             new \DateInterval('PT10M')
         );
-        $grant->enableCodeExchangeProof();
+
         $grant->setClientRepository($clientRepositoryMock);
         $grant->setAccessTokenRepository($accessTokenRepositoryMock);
         $grant->setRefreshTokenRepository($refreshTokenRepositoryMock);
@@ -1217,7 +1217,7 @@ class AuthCodeGrantTest extends TestCase
             $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
             new \DateInterval('PT10M')
         );
-        $grant->enableCodeExchangeProof();
+
         $grant->setClientRepository($clientRepositoryMock);
         $grant->setAccessTokenRepository($accessTokenRepositoryMock);
         $grant->setRefreshTokenRepository($refreshTokenRepositoryMock);
@@ -1289,7 +1289,7 @@ class AuthCodeGrantTest extends TestCase
             $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
             new \DateInterval('PT10M')
         );
-        $grant->enableCodeExchangeProof();
+
         $grant->setClientRepository($clientRepositoryMock);
         $grant->setAccessTokenRepository($accessTokenRepositoryMock);
         $grant->setRefreshTokenRepository($refreshTokenRepositoryMock);
@@ -1361,7 +1361,7 @@ class AuthCodeGrantTest extends TestCase
             $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
             new \DateInterval('PT10M')
         );
-        $grant->enableCodeExchangeProof();
+
         $grant->setClientRepository($clientRepositoryMock);
         $grant->setAccessTokenRepository($accessTokenRepositoryMock);
         $grant->setRefreshTokenRepository($refreshTokenRepositoryMock);
@@ -1433,7 +1433,7 @@ class AuthCodeGrantTest extends TestCase
             $this->getMockBuilder(RefreshTokenRepositoryInterface::class)->getMock(),
             new \DateInterval('PT10M')
         );
-        $grant->enableCodeExchangeProof();
+
         $grant->setClientRepository($clientRepositoryMock);
         $grant->setAccessTokenRepository($accessTokenRepositoryMock);
         $grant->setRefreshTokenRepository($refreshTokenRepositoryMock);