diff --git a/instructor/patch.py b/instructor/patch.py
index 3aabefd..3e364e9 100644
--- a/instructor/patch.py
+++ b/instructor/patch.py
@@ -1,17 +1,22 @@
 import inspect
-from functools import wraps
-from instructor.dsl.multitask import MultiTask, MultiTaskBase
-from json import JSONDecodeError
-from typing import get_origin, get_args, Callable, Optional, Type, Union
+import json
+import warnings
 from collections.abc import Iterable
+from functools import wraps
+from json import JSONDecodeError
+from typing import Callable, Optional, Type, Union, get_args, get_origin
 
 from openai import AsyncOpenAI, OpenAI
-from openai.types.chat import ChatCompletion
+from openai.types.chat import (
+    ChatCompletion,
+    ChatCompletionMessage,
+    ChatCompletionMessageParam,
+)
 from pydantic import BaseModel, ValidationError
 
-from .function_calls import OpenAISchema, openai_schema, Mode
+from instructor.dsl.multitask import MultiTask, MultiTaskBase
 
-import warnings
+from .function_calls import Mode, OpenAISchema, openai_schema
 
 OVERRIDE_DOCS = """
 Creates a new chat completion for the provided messages and parameters.
@@ -33,15 +38,20 @@ Parameters:
 """
 
 
-def dump_message(message) -> dict:
+def dump_message(message: ChatCompletionMessage) -> ChatCompletionMessageParam:
     """Dumps a message to a dict, to be returned to the OpenAI API.
     Workaround for an issue with the OpenAI API, where the `tool_calls` field isn't allowed to be present in requests
     if it isn't used.
     """
-    dumped_message = message.model_dump()
-    if not dumped_message.get("tool_calls"):
-        del dumped_message["tool_calls"]
-    return {k: v for k, v in dumped_message.items() if v}
+    ret: ChatCompletionMessageParam = {
+        "role": message.role,
+        "content": message.content or "",
+    }
+    if message.tool_calls is not None:
+        ret["content"] += json.dumps(message.model_dump()["tool_calls"])
+    if message.function_call is not None:
+        ret["content"] += json.dumps(message.model_dump()["function_call"])
+    return ret
 
 
 def handle_response_model(
@@ -202,7 +212,7 @@ def retry_sync(
                 mode=mode,
             )
         except (ValidationError, JSONDecodeError) as e:
-            kwargs["messages"].append(response.choices[0].message)
+            kwargs["messages"].append(dump_message(response.choices[0].message))
             kwargs["messages"].append(
                 {
                     "role": "user",
diff --git a/tests/test_patch.py b/tests/test_patch.py
index d6913d4..e8d2916 100644
--- a/tests/test_patch.py
+++ b/tests/test_patch.py
@@ -1,11 +1,16 @@
 import functools
+
 import pytest
+from openai import AsyncOpenAI, OpenAI
+from openai.types.chat import ChatCompletionMessage, ChatCompletionMessageParam
+from openai.types.chat.chat_completion_message import FunctionCall
+from openai.types.chat.chat_completion_message_tool_call import (
+    ChatCompletionMessageToolCall,
+    Function,
+)
+
 import instructor
-
-from openai import OpenAI, AsyncOpenAI
-
-
-from instructor.patch import is_async, wrap_chatcompletion, OVERRIDE_DOCS
+from instructor.patch import OVERRIDE_DOCS, dump_message, is_async, wrap_chatcompletion
 
 
 def test_patch_completes_successfully():
@@ -66,3 +71,106 @@ def test_override_docs():
     assert (
         "response_model" in OVERRIDE_DOCS
     ), "response_model should be in OVERRIDE_DOCS"
+
+
+@pytest.mark.parametrize(
+    "name_of_test, message, expected",
+    [
+        (
+            "tool_calls and content and no function_call",
+            ChatCompletionMessage(
+                role="assistant",
+                content="Hello, world!",
+                tool_calls=[
+                    ChatCompletionMessageToolCall(
+                        id="test_tool",
+                        function=Function(arguments="", name="test_tool"),
+                        type="function",
+                    )
+                ],
+            ),
+            {
+                "role": "assistant",
+                "content": 'Hello, world![{"id": "test_tool", "function": {"arguments": "", "name": "test_tool"}, "type": "function"}]',
+            },
+        ),
+        (
+            "tool_calls and no content and no function_call",
+            ChatCompletionMessage(
+                role="assistant",
+                content=None,
+                tool_calls=[
+                    ChatCompletionMessageToolCall(
+                        id="test_tool",
+                        function=Function(arguments="", name="test_tool"),
+                        type="function",
+                    )
+                ],
+            ),
+            {
+                "role": "assistant",
+                "content": '[{"id": "test_tool", "function": {"arguments": "", "name": "test_tool"}, "type": "function"}]',
+            },
+        ),
+        (
+            "no tool_calls and no content no function_call",
+            ChatCompletionMessage(
+                role="assistant",
+                content=None,
+            ),
+            {
+                "role": "assistant",
+                "content": "",
+            },
+        ),
+        (
+            "no tool_calls and content and function_call",
+            ChatCompletionMessage(
+                role="assistant",
+                content="Hello, world!",
+                function_call=FunctionCall(arguments="", name="test_tool"),
+            ),
+            {
+                "role": "assistant",
+                "content": 'Hello, world!{"arguments": "", "name": "test_tool"}',
+            },
+        ),
+        (
+            "no tool_calls and no content and function_call",
+            ChatCompletionMessage(
+                role="assistant",
+                content=None,
+                function_call=FunctionCall(arguments="", name="test_tool"),
+            ),
+            {
+                "role": "assistant",
+                "content": '{"arguments": "", "name": "test_tool"}',
+            },
+        ),
+        (
+            "tool_calls and no content and function_call",
+            ChatCompletionMessage(
+                role="assistant",
+                content=None,
+                function_call=FunctionCall(arguments="", name="test_tool"),
+                tool_calls=[
+                    ChatCompletionMessageToolCall(
+                        id="test_tool",
+                        function=Function(arguments="", name="test_tool"),
+                        type="function",
+                    )
+                ],
+            ),
+            {
+                "role": "assistant",
+                "content": '[{"id": "test_tool", "function": {"arguments": "", "name": "test_tool"}, "type": "function"}]{"arguments": "", "name": "test_tool"}',
+            },
+        ),
+    ],
+)
+def test_dump_message(
+    name_of_test: str,
+    message: ChatCompletionMessage,
+    expected: ChatCompletionMessageParam,
+):
+    assert dump_message(message) == expected, name_of_test