diff --git a/app/Plugin/OidcAuth/Lib/Oidc.php b/app/Plugin/OidcAuth/Lib/Oidc.php
index e2bb72c7d99..5390078a9f5 100644
--- a/app/Plugin/OidcAuth/Lib/Oidc.php
+++ b/app/Plugin/OidcAuth/Lib/Oidc.php
@@ -458,7 +458,7 @@ private function _findUser(array $settings, array $conditions)
     private function getConfig($config, $default = null)
     {
         $value = Configure::read("OidcAuth.$config");
-        if (empty($value)) {
+        if ($value === null) {
             if ($default === null) {
                 throw new RuntimeException("Config option `OidcAuth.$config` is not set.");
             }