diff --git a/src/Illuminate/Testing/TestResponse.php b/src/Illuminate/Testing/TestResponse.php
index 2f3d2ea32f45..0e9de3d5bcf6 100644
--- a/src/Illuminate/Testing/TestResponse.php
+++ b/src/Illuminate/Testing/TestResponse.php
@@ -906,7 +906,7 @@ public function assertJsonMissingPath(string $path)
      * @param  array|null  $responseData
      * @return $this
      */
-    public function assertJsonStructure(?array $structure = null, $responseData = null)
+    public function assertJsonStructure(?array $structure = null, ?array $responseData = null)
     {
         $this->decodeResponseJson()->assertStructure($structure, $responseData);
 
@@ -920,7 +920,7 @@ public function assertJsonStructure(?array $structure = null, $responseData = nu
      * @param  array|null  $responseData
      * @return $this
      */
-    public function assertExactJsonStructure(?array $structure = null, $responseData = null)
+    public function assertExactJsonStructure(?array $structure = null, ?array $responseData = null)
     {
         $this->decodeResponseJson()->assertStructure($structure, $responseData, true);