diff --git a/src/PrintNode/Credentials.php b/src/PrintNode/Credentials.php
index 571375a..1f11a8a 100755
--- a/src/PrintNode/Credentials.php
+++ b/src/PrintNode/Credentials.php
@@ -35,7 +35,7 @@ public function setEmailPassword($email, $password)
                 "ApiKey already set."
             );
 		}
-		$this->emailpassword = $email.': '.$password;
+		$this->emailPassword = $email.': '.$password;
 		return $this;
     }