diff --git a/litellm/litellm_core_utils/prompt_templates/factory.py b/litellm/litellm_core_utils/prompt_templates/factory.py
index 9ce138725fb..d7a6b4180be 100644
--- a/litellm/litellm_core_utils/prompt_templates/factory.py
+++ b/litellm/litellm_core_utils/prompt_templates/factory.py
@@ -2024,9 +2024,7 @@ def _is_empty_text_block(block: object) -> bool:
 
 
 def _survives_assistant_conversion(block: object) -> bool:
-    if not isinstance(block, dict):
-        return False
-    block_type = block.get("type")
+    block_type = block.get("type") if isinstance(block, dict) else None
     if not isinstance(block_type, str) or block_type == "text":
         return False
     if block_type == "thinking":
diff --git a/tests/test_litellm/llms/anthropic/test_message_sanitization.py b/tests/test_litellm/llms/anthropic/test_message_sanitization.py
index 9009f2d0799..c3c2a9ecd3e 100644
--- a/tests/test_litellm/llms/anthropic/test_message_sanitization.py
+++ b/tests/test_litellm/llms/anthropic/test_message_sanitization.py
@@ -508,8 +508,9 @@ class TestMessageSanitization:
             {"type": "image_url", "image_url": {"url": "data:image/png;base64,aGk="}},
             {"type": "thinking", "thinking": ""},
             {"type": "unknown_future_block"},
+            {"no_type_key": "malformed"},
         ],
-        ids=["image_url", "unsignable_thinking", "unknown_type"],
+        ids=["image_url", "unsignable_thinking", "unknown_type", "missing_type"],
     )
     def test_empty_text_kept_when_sibling_block_would_not_survive(self, sibling_block):
         """