diff --git a/src/Grant/AbstractGrant.php b/src/Grant/AbstractGrant.php
index 495a08f6..21909712 100644
--- a/src/Grant/AbstractGrant.php
+++ b/src/Grant/AbstractGrant.php
@@ -215,7 +215,7 @@ abstract class AbstractGrant implements GrantTypeInterface
         foreach ($scopesList as $scopeItem) {
             $scope = $this->scopeRepository->getScopeEntityByIdentifier($scopeItem);
 
-            if (($scope instanceof ScopeEntityInterface) === false) {
+            if (!$scope instanceof ScopeEntityInterface) {
                 throw OAuthServerException::invalidScope($scopeItem, $redirectUri);
             }
 
diff --git a/src/Grant/AuthCodeGrant.php b/src/Grant/AuthCodeGrant.php
index 5540dd25..569d72f1 100644
--- a/src/Grant/AuthCodeGrant.php
+++ b/src/Grant/AuthCodeGrant.php
@@ -4,6 +4,7 @@ namespace League\OAuth2\Server\Grant;
 
 use DateInterval;
 use League\OAuth2\Server\Entities\ClientEntityInterface;
+use League\OAuth2\Server\Entities\ScopeEntityInterface;
 use League\OAuth2\Server\Entities\UserEntityInterface;
 use League\OAuth2\Server\Exception\OAuthServerException;
 use League\OAuth2\Server\Repositories\AuthCodeRepositoryInterface;
@@ -90,7 +91,7 @@ class AuthCodeGrant extends AbstractAuthorizeGrant
             foreach ($authCodePayload->scopes as $scopeId) {
                 $scope = $this->scopeRepository->getScopeEntityByIdentifier($scopeId);
 
-                if ($scope === false) {
+                if (!$scope instanceof ScopeEntityInterface) {
                     // @codeCoverageIgnoreStart
                     throw OAuthServerException::invalidScope($scopeId);
                     // @codeCoverageIgnoreEnd
diff --git a/src/Grant/RefreshTokenGrant.php b/src/Grant/RefreshTokenGrant.php
index 0e27af45..0d65fae6 100644
--- a/src/Grant/RefreshTokenGrant.php
+++ b/src/Grant/RefreshTokenGrant.php
@@ -10,6 +10,7 @@
  */
 namespace League\OAuth2\Server\Grant;
 
+use League\OAuth2\Server\Entities\ScopeEntityInterface;
 use League\OAuth2\Server\Exception\OAuthServerException;
 use League\OAuth2\Server\Repositories\RefreshTokenRepositoryInterface;
 use League\OAuth2\Server\RequestEvent;
@@ -49,7 +50,7 @@ class RefreshTokenGrant extends AbstractGrant
             $scopes = array_map(function ($scopeId) use ($client) {
                 $scope = $this->scopeRepository->getScopeEntityByIdentifier($scopeId);
 
-                if (!$scope) {
+                if (!$scope instanceof ScopeEntityInterface) {
                     // @codeCoverageIgnoreStart
                     throw OAuthServerException::invalidScope($scopeId);
                     // @codeCoverageIgnoreEnd