diff --git a/src/Storage/AccessTokenInterface.php b/src/Storage/AccessTokenInterface.php
index 5f852b80..129679dd 100644
--- a/src/Storage/AccessTokenInterface.php
+++ b/src/Storage/AccessTokenInterface.php
@@ -24,7 +24,7 @@ interface AccessTokenInterface extends StorageInterface
      *
      * @param string $token The access token
      *
-     * @return \League\OAuth2\Server\Entity\AccessTokenEntity
+     * @return \League\OAuth2\Server\Entity\AccessTokenEntity | null
      */
     public function get($token);
 
@@ -33,7 +33,7 @@ interface AccessTokenInterface extends StorageInterface
      *
      * @param \League\OAuth2\Server\Entity\AccessTokenEntity $token The access token
      *
-     * @return array Array of \League\OAuth2\Server\Entity\ScopeEntity
+     * @return \League\OAuth2\Server\Entity\ScopeEntity[] Array of \League\OAuth2\Server\Entity\ScopeEntity
      */
     public function getScopes(AccessTokenEntity $token);
 
diff --git a/src/Storage/AuthCodeInterface.php b/src/Storage/AuthCodeInterface.php
index 1fe0f8b9..d451d2ef 100644
--- a/src/Storage/AuthCodeInterface.php
+++ b/src/Storage/AuthCodeInterface.php
@@ -24,7 +24,7 @@ interface AuthCodeInterface extends StorageInterface
      *
      * @param string $code
      *
-     * @return \League\OAuth2\Server\Entity\AuthCodeEntity
+     * @return \League\OAuth2\Server\Entity\AuthCodeEntity | null
      */
     public function get($code);
 
@@ -45,7 +45,7 @@ interface AuthCodeInterface extends StorageInterface
      *
      * @param \League\OAuth2\Server\Entity\AuthCodeEntity $token The auth code
      *
-     * @return array Array of \League\OAuth2\Server\Entity\ScopeEntity
+     * @return \League\OAuth2\Server\Entity\ScopeEntity[] Array of \League\OAuth2\Server\Entity\ScopeEntity
      */
     public function getScopes(AuthCodeEntity $token);
 
diff --git a/src/Storage/ClientInterface.php b/src/Storage/ClientInterface.php
index 4e9cc39a..e8968316 100644
--- a/src/Storage/ClientInterface.php
+++ b/src/Storage/ClientInterface.php
@@ -26,7 +26,7 @@ interface ClientInterface extends StorageInterface
      * @param string $redirectUri  The client's redirect URI (default = "null")
      * @param string $grantType    The grant type used (default = "null")
      *
-     * @return \League\OAuth2\Server\Entity\ClientEntity
+     * @return \League\OAuth2\Server\Entity\ClientEntity | null
      */
     public function get($clientId, $clientSecret = null, $redirectUri = null, $grantType = null);
 
@@ -35,7 +35,7 @@ interface ClientInterface extends StorageInterface
      *
      * @param \League\OAuth2\Server\Entity\SessionEntity $session The session
      *
-     * @return \League\OAuth2\Server\Entity\ClientEntity
+     * @return \League\OAuth2\Server\Entity\ClientEntity | null
      */
     public function getBySession(SessionEntity $session);
 }
diff --git a/src/Storage/RefreshTokenInterface.php b/src/Storage/RefreshTokenInterface.php
index bf65468c..e2f19959 100644
--- a/src/Storage/RefreshTokenInterface.php
+++ b/src/Storage/RefreshTokenInterface.php
@@ -23,7 +23,7 @@ interface RefreshTokenInterface extends StorageInterface
      *
      * @param string $token
      *
-     * @return \League\OAuth2\Server\Entity\RefreshTokenEntity
+     * @return \League\OAuth2\Server\Entity\RefreshTokenEntity | null
      */
     public function get($token);
 
diff --git a/src/Storage/ScopeInterface.php b/src/Storage/ScopeInterface.php
index e8bc10b0..1257a819 100644
--- a/src/Storage/ScopeInterface.php
+++ b/src/Storage/ScopeInterface.php
@@ -23,7 +23,7 @@ interface ScopeInterface extends StorageInterface
      * @param string $grantType The grant type used in the request (default = "null")
      * @param string $clientId  The client sending the request (default = "null")
      *
-     * @return \League\OAuth2\Server\Entity\ScopeEntity
+     * @return \League\OAuth2\Server\Entity\ScopeEntity | null
      */
     public function get($scope, $grantType = null, $clientId = null);
 }
diff --git a/src/Storage/SessionInterface.php b/src/Storage/SessionInterface.php
index ab205180..bc70e8f6 100644
--- a/src/Storage/SessionInterface.php
+++ b/src/Storage/SessionInterface.php
@@ -26,7 +26,7 @@ interface SessionInterface extends StorageInterface
      *
      * @param \League\OAuth2\Server\Entity\AccessTokenEntity $accessToken The access token
      *
-     * @return \League\OAuth2\Server\Entity\SessionEntity
+     * @return \League\OAuth2\Server\Entity\SessionEntity | null
      */
     public function getByAccessToken(AccessTokenEntity $accessToken);
 
@@ -35,7 +35,7 @@ interface SessionInterface extends StorageInterface
      *
      * @param \League\OAuth2\Server\Entity\AuthCodeEntity $authCode The auth code
      *
-     * @return \League\OAuth2\Server\Entity\SessionEntity
+     * @return \League\OAuth2\Server\Entity\SessionEntity | null
      */
     public function getByAuthCode(AuthCodeEntity $authCode);
 
@@ -44,7 +44,7 @@ interface SessionInterface extends StorageInterface
      *
      * @param  \League\OAuth2\Server\Entity\SessionEntity
      *
-     * @return array Array of \League\OAuth2\Server\Entity\ScopeEntity
+     * @return \League\OAuth2\Server\Entity\ScopeEntity[] Array of \League\OAuth2\Server\Entity\ScopeEntity
      */
     public function getScopes(SessionEntity $session);