diff --git a/src/Grant/AuthCodeGrant.php b/src/Grant/AuthCodeGrant.php
index e3e10363..2d8fb5db 100644
--- a/src/Grant/AuthCodeGrant.php
+++ b/src/Grant/AuthCodeGrant.php
@@ -173,7 +173,7 @@ class AuthCodeGrant extends AbstractGrant
 
         $clientSecret = $this->server->getRequest()->request->get('client_secret', null);
         if (is_null($clientSecret)) {
-            $clientId = $this->server->getRequest()->getPassword();
+            $clientSecret = $this->server->getRequest()->getPassword();
             if (is_null($clientSecret)) {
                 throw new Exception\InvalidRequestException('client_secret');
             }
diff --git a/src/Grant/ClientCredentialsGrant.php b/src/Grant/ClientCredentialsGrant.php
index 3541d546..442d6f84 100644
--- a/src/Grant/ClientCredentialsGrant.php
+++ b/src/Grant/ClientCredentialsGrant.php
@@ -64,7 +64,7 @@ class ClientCredentialsGrant extends AbstractGrant
 
         $clientSecret = $this->server->getRequest()->request->get('client_secret', null);
         if (is_null($clientSecret)) {
-            $clientId = $this->server->getRequest()->getPassword();
+            $clientSecret = $this->server->getRequest()->getPassword();
             if (is_null($clientSecret)) {
                 throw new Exception\InvalidRequestException('client_secret');
             }
diff --git a/src/Grant/PasswordGrant.php b/src/Grant/PasswordGrant.php
index 21f89cb3..6e90aa19 100644
--- a/src/Grant/PasswordGrant.php
+++ b/src/Grant/PasswordGrant.php
@@ -88,7 +88,7 @@ class PasswordGrant extends AbstractGrant
 
         $clientSecret = $this->server->getRequest()->request->get('client_secret', null);
         if (is_null($clientSecret)) {
-            $clientId = $this->server->getRequest()->getPassword();
+            $clientSecret = $this->server->getRequest()->getPassword();
             if (is_null($clientSecret)) {
                 throw new Exception\InvalidRequestException('client_secret');
             }
diff --git a/src/Grant/RefreshTokenGrant.php b/src/Grant/RefreshTokenGrant.php
index 92b116f8..f757560c 100644
--- a/src/Grant/RefreshTokenGrant.php
+++ b/src/Grant/RefreshTokenGrant.php
@@ -68,7 +68,7 @@ class RefreshTokenGrant extends AbstractGrant
 
         $clientSecret = $this->server->getRequest()->request->get('client_secret', null);
         if (is_null($clientSecret)) {
-            $clientId = $this->server->getRequest()->getPassword();
+            $clientSecret = $this->server->getRequest()->getPassword();
             if (is_null($clientSecret)) {
                 throw new Exception\InvalidRequestException('client_secret');
             }