diff --git a/tests/test_custom_pickler.py b/tests/test_custom_pickler.py
new file mode 100644
index 00000000..b465b8eb
--- /dev/null
+++ b/tests/test_custom_pickler.py
@@ -0,0 +1,63 @@
+import os
+import pytest
+from io import BytesIO
+from typing import List
+from pydantic import BaseModel
+
+from bespokelabs.curator.utils.custom_pickler import CustomPickler, dumps, loads
+
+class TestModel(BaseModel):
+    value: str
+    items: List[int]
+
+def test_custom_pickler_type_annotations():
+    """Test CustomPickler handles type annotations correctly."""
+    def func(x: TestModel) -> List[int]:
+        return x.items
+    
+    # Test pickling and unpickling
+    pickled = dumps(func)
+    unpickled = loads(pickled)
+    
+    # Test function still works
+    test_input = TestModel(value="test", items=[1, 2, 3])
+    assert unpickled(test_input) == [1, 2, 3]
+
+def test_custom_pickler_path_normalization():
+    """Test CustomPickler normalizes paths in function source."""
+    def func():
+        path = os.path.join("/home", "user", "file.txt")
+        return path
+    
+    # Pickle in one directory
+    original_dir = os.getcwd()
+    try:
+        os.chdir("/tmp")
+        pickled1 = dumps(func)
+        
+        # Pickle in another directory
+        os.chdir("/home")
+        pickled2 = dumps(func)
+        
+        # Hashes should match despite different directories
+        assert pickled1 == pickled2
+    finally:
+        os.chdir(original_dir)
+
+def test_custom_pickler_hybrid_serialization():
+    """Test CustomPickler falls back to cloudpickle for type annotations."""
+    def func(x: TestModel, items: List[int]) -> List[int]:
+        return [i for i in items if i > int(x.value)]
+    
+    # Test pickling with both type annotations and path-dependent code
+    file = BytesIO()
+    pickler = CustomPickler(file, recurse=True)
+    pickler.dump(func)
+    
+    # Test unpickling
+    file.seek(0)
+    unpickled = loads(file.getvalue())
+    
+    # Test function works
+    test_input = TestModel(value="2", items=[1, 2, 3])
+    assert unpickled(test_input, [1, 2, 3, 4]) == [3, 4]
diff --git a/tests/test_prompt.py b/tests/test_prompt.py
index 2a2af520..bac082fa 100644
--- a/tests/test_prompt.py
+++ b/tests/test_prompt.py
@@ -105,7 +105,7 @@ def simple_prompt_func(row: _DictOrBaseModel) -> _DictOrBaseModel:
         Returns:
             A list of messages for the LLM
         """
-        return [
+        messages = [
             {
                 "role": "user",
                 "content": "Write a test message",
@@ -115,7 +115,10 @@ def simple_prompt_func(row: _DictOrBaseModel) -> _DictOrBaseModel:
                 "content": "You are a helpful assistant.",
             },
         ]
+        return {"messages": messages}
 
+    # Set dummy OpenAI API key for testing
+    os.environ["OPENAI_API_KEY"] = "test-key"
     batch_prompter = LLM(
         model_name="gpt-4o-mini",
         prompt_func=simple_prompt_func,
@@ -162,7 +165,7 @@ def simple_prompt_func(row: _DictOrBaseModel) -> _DictOrBaseModel:
         Returns:
             A list of messages for the LLM
         """
-        return [
+        messages = [
             {
                 "role": "user",
                 "content": "Write a test message",
@@ -172,7 +175,10 @@ def simple_prompt_func(row: _DictOrBaseModel) -> _DictOrBaseModel:
                 "content": "You are a helpful assistant.",
             },
         ]
+        return {"messages": messages}
 
+    # Set dummy OpenAI API key for testing
+    os.environ["OPENAI_API_KEY"] = "test-key"
     non_batch_prompter = LLM(
         model_name="gpt-4o-mini",
         prompt_func=simple_prompt_func,