diff --git a/src/Grant/AbstractGrant.php b/src/Grant/AbstractGrant.php
index f700c57b..9b3592c5 100644
--- a/src/Grant/AbstractGrant.php
+++ b/src/Grant/AbstractGrant.php
@@ -226,7 +226,7 @@ abstract class AbstractGrant implements GrantTypeInterface
     /**
      * Validate scopes in the request.
      *
-     * @param \Psr\Http\Message\ServerRequestInterface                        $request
+     * @param string                                                          $scopes
      * @param \League\OAuth2\Server\Entities\Interfaces\ClientEntityInterface $client
      * @param string                                                          $redirectUri
      *
@@ -235,13 +235,12 @@ abstract class AbstractGrant implements GrantTypeInterface
      * @return \League\OAuth2\Server\Entities\ScopeEntity[]
      */
     public function validateScopes(
-        ServerRequestInterface $request,
+        $scopes,
         ClientEntityInterface $client,
         $redirectUri = null
     ) {
-        $requestedScopes = $this->getRequestParameter('scope', $request);
         $scopesList = array_filter(
-            explode(self::SCOPE_DELIMITER_STRING, trim($requestedScopes)),
+            explode(self::SCOPE_DELIMITER_STRING, trim($scopes)),
             function ($scope) {
                 return !empty($scope);
             }
diff --git a/src/Grant/AuthCodeGrant.php b/src/Grant/AuthCodeGrant.php
index ca54b824..6f3d6dfb 100644
--- a/src/Grant/AuthCodeGrant.php
+++ b/src/Grant/AuthCodeGrant.php
@@ -94,7 +94,11 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
             throw OAuthServerException::invalidClient();
         }
 
-        $scopes = $this->validateScopes($request, $client, $client->getRedirectUri());
+        $scopes = $this->validateScopes(
+            $this->getQueryStringParameter('scope', $request),
+            $client,
+            $client->getRedirectUri()
+        );
         $queryString = http_build_query($request->getQueryParams());
         $postbackUri = new Uri(
             sprintf(
diff --git a/src/Grant/ClientCredentialsGrant.php b/src/Grant/ClientCredentialsGrant.php
index 6da17f21..1b15defd 100644
--- a/src/Grant/ClientCredentialsGrant.php
+++ b/src/Grant/ClientCredentialsGrant.php
@@ -28,7 +28,7 @@ class ClientCredentialsGrant extends AbstractGrant
     ) {
         // Validate request
         $client = $this->validateClient($request);
-        $scopes = $this->validateScopes($request, $client);
+        $scopes = $this->validateScopes($this->getRequestParameter('scope', $request), $client);
 
         // Issue and persist access token
         $accessToken = $this->issueAccessToken($accessTokenTTL, $client, $client->getIdentifier(), $scopes);
diff --git a/src/Grant/ImplicitGrant.php b/src/Grant/ImplicitGrant.php
index c3541ad3..7f846f90 100644
--- a/src/Grant/ImplicitGrant.php
+++ b/src/Grant/ImplicitGrant.php
@@ -94,7 +94,11 @@ class ImplicitGrant extends AbstractAuthorizeGrant
             throw OAuthServerException::invalidClient();
         }
 
-        $scopes = $this->validateScopes($request, $client, $client->getRedirectUri());
+        $scopes = $this->validateScopes(
+            $this->getQueryStringParameter('scope', $request),
+            $client,
+            $client->getRedirectUri()
+        );
         $queryString = http_build_query($request->getQueryParams());
         $postbackUri = new Uri(
             sprintf(
diff --git a/src/Grant/PasswordGrant.php b/src/Grant/PasswordGrant.php
index 1145e6ab..d7328f71 100644
--- a/src/Grant/PasswordGrant.php
+++ b/src/Grant/PasswordGrant.php
@@ -53,7 +53,7 @@ class PasswordGrant extends AbstractGrant
         // Validate request
         $client = $this->validateClient($request);
         $user = $this->validateUser($request);
-        $scopes = $this->validateScopes($request, $client);
+        $scopes = $this->validateScopes($this->getRequestParameter('scope', $request), $client);
 
         // Issue and persist new tokens
         $accessToken = $this->issueAccessToken($accessTokenTTL, $client, $user->getIdentifier(), $scopes);
diff --git a/src/Grant/RefreshTokenGrant.php b/src/Grant/RefreshTokenGrant.php
index 83ffe5ed..efcc6454 100644
--- a/src/Grant/RefreshTokenGrant.php
+++ b/src/Grant/RefreshTokenGrant.php
@@ -44,7 +44,7 @@ class RefreshTokenGrant extends AbstractGrant
         // Validate request
         $client = $this->validateClient($request);
         $oldRefreshToken = $this->validateOldRefreshToken($request, $client->getIdentifier());
-        $scopes = $this->validateScopes($request, $client);
+        $scopes = $this->validateScopes($this->getRequestParameter('scope', $request), $client);
 
         // If no new scopes are requested then give the access token the original session scopes
         if (count($scopes) === 0) {
diff --git a/tests/Grant/AbstractGrantTest.php b/tests/Grant/AbstractGrantTest.php
index a2b764d2..8fbf7626 100644
--- a/tests/Grant/AbstractGrantTest.php
+++ b/tests/Grant/AbstractGrantTest.php
@@ -343,14 +343,7 @@ class AbstractGrantTest extends \PHPUnit_Framework_TestCase
         $grantMock = $this->getMockForAbstractClass(AbstractGrant::class);
         $grantMock->setScopeRepository($scopeRepositoryMock);
 
-        $serverRequest = new ServerRequest();
-        $serverRequest = $serverRequest->withParsedBody(
-            [
-                'scope' => 'basic   ',
-            ]
-        );
-
-        $this->assertEquals([$scope], $grantMock->validateScopes($serverRequest, new ClientEntity()));
+        $this->assertEquals([$scope], $grantMock->validateScopes('basic   ', new ClientEntity()));
     }
 
     /**
@@ -365,14 +358,7 @@ class AbstractGrantTest extends \PHPUnit_Framework_TestCase
         $grantMock = $this->getMockForAbstractClass(AbstractGrant::class);
         $grantMock->setScopeRepository($scopeRepositoryMock);
 
-        $serverRequest = new ServerRequest();
-        $serverRequest = $serverRequest->withParsedBody(
-            [
-                'scope' => 'basic   ',
-            ]
-        );
-
-        $grantMock->validateScopes($serverRequest, new ClientEntity());
+        $grantMock->validateScopes('basic   ', new ClientEntity());
     }
 
     public function testGenerateUniqueIdentifier()