diff --git a/src/Model/SchemaDefinition/JsonSchema.php b/src/Model/SchemaDefinition/JsonSchema.php
index adfe9cd..df0cf22 100644
--- a/src/Model/SchemaDefinition/JsonSchema.php
+++ b/src/Model/SchemaDefinition/JsonSchema.php
@@ -48,16 +48,18 @@ public function __construct(string $file, array $json)
     {
         // wrap in an allOf to pass the processing to multiple handlers - ugly hack to be removed after rework
         if (isset($json['$ref']) && count(array_diff(array_intersect(array_keys($json), self::SCHEMA_SIGNATURE_RELEVANT_FIELDS), ['$ref', 'type']))) {
-            $json = [
-                ...array_diff_key($json, array_fill_keys(self::SCHEMA_SIGNATURE_RELEVANT_FIELDS, null)),
-                'allOf' => [
-                    ['$ref' => $json['$ref']],
-                    array_intersect_key(
-                        $json,
-                        array_fill_keys(array_diff(self::SCHEMA_SIGNATURE_RELEVANT_FIELDS, ['$ref']), null),
-                    ),
+            $json = array_merge(
+                array_diff_key($json, array_fill_keys(self::SCHEMA_SIGNATURE_RELEVANT_FIELDS, null)),
+                [
+                    'allOf' => [
+                        ['$ref' => $json['$ref']],
+                        array_intersect_key(
+                            $json,
+                            array_fill_keys(array_diff(self::SCHEMA_SIGNATURE_RELEVANT_FIELDS, ['$ref']), null),
+                        ),
+                    ],
                 ],
-            ];
+            );
         }
 
         $this->json = $json;