diff --git a/tests/test_litellm/llms/vertex_ai/test_vertex_ai_common_utils.py b/tests/test_litellm/llms/vertex_ai/test_vertex_ai_common_utils.py
index 7842f425926..0bd7f41676d 100644
--- a/tests/test_litellm/llms/vertex_ai/test_vertex_ai_common_utils.py
+++ b/tests/test_litellm/llms/vertex_ai/test_vertex_ai_common_utils.py
@@ -226,6 +226,7 @@ def test_build_vertex_schema():
                     "callbacks": {
                         "anyOf": [
                             {"type": "array", "nullable": True},
+                            {"nullable": True},
                         ]
                     },
                     "run_name": {"type": "string"},