diff --git a/src/Grant/AbstractGrant.php b/src/Grant/AbstractGrant.php
index e34436e5..c34e65cf 100644
--- a/src/Grant/AbstractGrant.php
+++ b/src/Grant/AbstractGrant.php
@@ -174,27 +174,24 @@ abstract class AbstractGrant implements GrantTypeInterface
         list($basicAuthUser, $basicAuthPassword) = $this->getBasicAuthCredentials($request);
 
         $clientId = $this->getRequestParameter('client_id', $request, $basicAuthUser);
+
         if (is_null($clientId)) {
             throw OAuthServerException::invalidRequest('client_id');
         }
 
-        // If the client is confidential require the client secret
         $clientSecret = $this->getRequestParameter('client_secret', $request, $basicAuthPassword);
 
-        $client = $this->clientRepository->getClientEntity(
-            $clientId,
-            $this->getIdentifier(),
-            $clientSecret,
-            true
-        );
-
-        if ($client instanceof ClientEntityInterface === false) {
+        if ($this->clientRepository->validateClient($clientId, $clientSecret) === false) {
             $this->getEmitter()->emit(new RequestEvent(RequestEvent::CLIENT_AUTHENTICATION_FAILED, $request));
+
             throw OAuthServerException::invalidClient($request);
         }
 
+        $client = $this->clientRepository->getClientEntity($clientId);
+
         // If a redirect URI is provided ensure it matches what is pre-registered
         $redirectUri = $this->getRequestParameter('redirect_uri', $request, null);
+        
         if ($redirectUri !== null) {
             $this->validateRedirectUri($redirectUri, $client, $request);
         }
diff --git a/src/Repositories/ClientRepositoryInterface.php b/src/Repositories/ClientRepositoryInterface.php
index 9e863af8..d390a5f6 100644
--- a/src/Repositories/ClientRepositoryInterface.php
+++ b/src/Repositories/ClientRepositoryInterface.php
@@ -19,15 +19,11 @@ interface ClientRepositoryInterface extends RepositoryInterface
     /**
      * Get a client.
      *
-     * @param string      $clientIdentifier   The client's identifier
-     * @param null|string $grantType          The grant type used (if sent)
-     * @param null|string $clientSecret       The client's secret (if sent)
-     * @param bool        $mustValidateSecret If true the client must attempt to validate the secret if the client
-     *                                        is confidential
+     * @param string $clientIdentifier The client's identifier
      *
      * @return ClientEntityInterface
      */
-    public function getClientEntity($clientIdentifier, $grantType = null, $clientSecret = null, $mustValidateSecret = true);
+    public function getClientEntity($clientIdentifier);
 
     /**
      * Check if a client is confidential.
@@ -37,4 +33,21 @@ interface ClientRepositoryInterface extends RepositoryInterface
      * @return bool
      */
     public function isClientConfidential($clientIdentifier);
+
+    /**
+     * Validate a client's secret.
+     *
+     * @param string      $clientIdentifier The client's identifier
+     * @param null|string $clientSecret     The client's secret (if sent)
+     *
+     * @return bool
+     */
+    public function validateClient($clientIdentifier, $clientSecret);
+
+    /**
+     * Check if a client can use a grant type.
+     *
+     * @return bool
+     */
+    public function canUseGrant($clientIdentifier, $grantType);
 }
diff --git a/tests/Exception/OAuthServerExceptionTest.php b/tests/Exception/OAuthServerExceptionTest.php
index cead7d6a..8efce51f 100644
--- a/tests/Exception/OAuthServerExceptionTest.php
+++ b/tests/Exception/OAuthServerExceptionTest.php
@@ -52,7 +52,7 @@ class OAuthServerExceptionTest extends TestCase
     private function issueInvalidClientException($serverRequest)
     {
         $clientRepositoryMock = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
-        $clientRepositoryMock->method('getClientEntity')->willReturn(false);
+        $clientRepositoryMock->method('validateClient')->willReturn(false);
 
         $grantMock = $this->getMockForAbstractClass(AbstractGrant::class);
         $grantMock->setClientRepository($clientRepositoryMock);
diff --git a/tests/Grant/AbstractGrantTest.php b/tests/Grant/AbstractGrantTest.php
index 64fde4f0..d6ddd4b1 100644
--- a/tests/Grant/AbstractGrantTest.php
+++ b/tests/Grant/AbstractGrantTest.php
@@ -175,7 +175,7 @@ class AbstractGrantTest extends TestCase
     public function testValidateClientMissingClientSecret()
     {
         $clientRepositoryMock = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
-        $clientRepositoryMock->method('getClientEntity')->willReturn(null);
+        $clientRepositoryMock->method('validateClient')->willReturn(false);
 
         /** @var AbstractGrant $grantMock */
         $grantMock = $this->getMockForAbstractClass(AbstractGrant::class);
@@ -200,7 +200,7 @@ class AbstractGrantTest extends TestCase
     public function testValidateClientInvalidClientSecret()
     {
         $clientRepositoryMock = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
-        $clientRepositoryMock->method('getClientEntity')->willReturn(null);
+        $clientRepositoryMock->method('validateClient')->willReturn(false);
 
         /** @var AbstractGrant $grantMock */
         $grantMock = $this->getMockForAbstractClass(AbstractGrant::class);
@@ -282,7 +282,7 @@ class AbstractGrantTest extends TestCase
     public function testValidateClientBadClient()
     {
         $clientRepositoryMock = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
-        $clientRepositoryMock->method('getClientEntity')->willReturn(null);
+        $clientRepositoryMock->method('validateClient')->willReturn(false);
 
         /** @var AbstractGrant $grantMock */
         $grantMock = $this->getMockForAbstractClass(AbstractGrant::class);
diff --git a/tests/Middleware/AuthorizationServerMiddlewareTest.php b/tests/Middleware/AuthorizationServerMiddlewareTest.php
index 99118736..dcfcfbd9 100644
--- a/tests/Middleware/AuthorizationServerMiddlewareTest.php
+++ b/tests/Middleware/AuthorizationServerMiddlewareTest.php
@@ -66,7 +66,7 @@ class AuthorizationServerMiddlewareTest extends TestCase
     public function testOAuthErrorResponse()
     {
         $clientRepository = $this->getMockBuilder(ClientRepositoryInterface::class)->getMock();
-        $clientRepository->method('getClientEntity')->willReturn(null);
+        $clientRepository->method('validateClient')->willReturn(false);
 
         $server = new AuthorizationServer(
             $clientRepository,