diff --git a/google/genai/tests/types/test_types.py b/google/genai/tests/types/test_types.py
index 50a3f9058..7c06b85bb 100644
--- a/google/genai/tests/types/test_types.py
+++ b/google/genai/tests/types/test_types.py
@@ -24,6 +24,14 @@
 import pytest
 from ... import types
 
+
+def test_finish_reason_malformed_response():
+  assert types.FinishReason.MALFORMED_RESPONSE.value == 'MALFORMED_RESPONSE'
+  assert (
+      types.FinishReason('MALFORMED_RESPONSE')
+      is types.FinishReason.MALFORMED_RESPONSE
+  )
+
 _is_mcp_imported = False
 if typing.TYPE_CHECKING:
   from mcp import types as mcp_types
diff --git a/google/genai/types.py b/google/genai/types.py
index 24d739ee8..10b242c70 100644
--- a/google/genai/types.py
+++ b/google/genai/types.py
@@ -513,6 +513,8 @@ class FinishReason(_common.CaseInSensitiveEnum):
   """Token generation stopped because the content potentially contains Sensitive Personally Identifiable Information (SPII)."""
   MALFORMED_FUNCTION_CALL = 'MALFORMED_FUNCTION_CALL'
   """The function call generated by the model is invalid."""
+  MALFORMED_RESPONSE = 'MALFORMED_RESPONSE'
+  """The model response was malformed."""
   IMAGE_SAFETY = 'IMAGE_SAFETY'
   """Token generation stopped because generated images have safety violations."""
   UNEXPECTED_TOOL_CALL = 'UNEXPECTED_TOOL_CALL'