diff --git a/src/ResourceType/ConfigurableResourceTypeRepository.php b/src/ResourceType/ConfigurableResourceTypeRepository.php
index c377969e29d35b942cb95def17e6cd37be41e429..8baf8e6c1d6a5087bf74e342f7f64e9d382fbfe1 100644
--- a/src/ResourceType/ConfigurableResourceTypeRepository.php
+++ b/src/ResourceType/ConfigurableResourceTypeRepository.php
@@ -73,15 +73,23 @@ class ConfigurableResourceTypeRepository extends ResourceTypeRepository {
    * @todo Remove this when JSON API Extras drops support for JSON API 1.x.
    */
   public static function isJsonApi2x() {
-    static $result = NULL;
+    static $is_2x = NULL;
 
-    if ($result === NULL) {
-      $v = ModuleHandler::parseDependency('jsonapi(>= 8.x-2.0-beta1)');
-      $module_list = \Drupal::service('extension.list.module')->getList();
-      $result = NULL === drupal_check_incompatibility($v, $module_list['jsonapi']->info['version']);
+    if ($is_2x !== NULL) {
+      return $is_2x;
     }
-
-    return $result;
+    $extension = \Drupal::service('extension.list.module')->get('jsonapi');
+    $version = $extension->info['version'];
+    if ($version === NULL) {
+      // When running a git clone of the module we will not get a version number
+      // here. In this case we resort to checking for a 2.x only service.
+      $is_2x = \Drupal::hasService('jsonapi.include_resolver');
+    }
+    else {
+      $dependency = ModuleHandler::parseDependency('jsonapi(>= 8.x-2.0-beta1)');
+      $is_2x = drupal_check_incompatibility($dependency, $version) === NULL;
+    }
+    return $is_2x;
   }
 
   /**