diff --git a/controller.py b/controller.py
index 0f0bc6a..01a8a4b 100644
--- a/controller.py
+++ b/controller.py
@@ -77,7 +77,9 @@ class AutoDLClient:
             "/api/v1/dev/instance/pro/image/private/list",
             {"page_index": 1, "page_size": 100},
         )
-        return list(data.get("list", []))
+        # AutoDL returns JSON null instead of [] when the account has no
+        # private images. Treat both representations as an empty result.
+        return list(data.get("list") or [])
 
     def create(self, spec: dict[str, Any]) -> str:
         return str(self.request("POST", "/api/v1/dev/instance/pro/create", spec))
diff --git a/tests/test_controller.py b/tests/test_controller.py
index 6e7beec..8b8a5ca 100644
--- a/tests/test_controller.py
+++ b/tests/test_controller.py
@@ -8,6 +8,12 @@ import controller
 
 
 class ControllerTests(unittest.TestCase):
+    def test_list_images_accepts_null_for_an_empty_account(self):
+        client = controller.AutoDLClient("test-token")
+        client.request = lambda method, path, body: {"list": None}
+
+        self.assertEqual(client.list_images(), [])
+
     def test_runner_release_is_pinned(self):
         self.assertEqual(controller.RUNNER_VERSION, "3.5.0")
         self.assertEqual(len(controller.RUNNER_SHA256), 64)