diff --git a/core/modules/rest/src/Plugin/rest/resource/EntityResource.php b/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
index 8cf6cb236a..f79ee1f551 100644
--- a/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
+++ b/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
@@ -394,7 +394,7 @@ protected function getBaseRoute($canonical_path, $method) {
    */
   public function availableMethods() {
     $methods = parent::availableMethods();
-    if ($this->isConfigEntityResource() && !empty($this->entityType->get('rest_resource'))) {
+    if ($this->isConfigEntityResource() && empty($this->entityType->get('rest_resource'))) {
       // Currently only GET is supported for Config Entities.
       // @todo Remove when supported https://www.drupal.org/node/2300677
       $unsupported_methods = ['POST', 'PUT', 'DELETE', 'PATCH'];