diff --git a/src/finch/_base_client.py b/src/finch/_base_client.py
index 7a8595c1..ebf39f15 100644
--- a/src/finch/_base_client.py
+++ b/src/finch/_base_client.py
@@ -361,6 +361,11 @@ def __init__(
         self._strict_response_validation = _strict_response_validation
         self._idempotency_header = None
 
+        if max_retries is None:  # pyright: ignore[reportUnnecessaryComparison]
+            raise TypeError(
+                "max_retries cannot be None. If you want to disable retries, pass `0`; if you want unlimited retries, pass `math.inf` or a very high number; if you want the default behavior, pass `finch-api.DEFAULT_MAX_RETRIES`"
+            )
+
     def _enforce_trailing_slash(self, url: URL) -> URL:
         if url.raw_path.endswith(b"/"):
             return url
diff --git a/tests/test_client.py b/tests/test_client.py
index 64706426..0995ec32 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -875,6 +875,17 @@ class Model(BaseModel):
 
         assert isinstance(exc.value.__cause__, ValidationError)
 
+    def test_client_max_retries_validation(self) -> None:
+        with pytest.raises(TypeError, match=r"max_retries cannot be None"):
+            Finch(
+                base_url=base_url,
+                access_token=access_token,
+                client_id=client_id,
+                client_secret=client_secret,
+                _strict_response_validation=True,
+                max_retries=cast(Any, None),
+            )
+
     @pytest.mark.respx(base_url=base_url)
     def test_received_text_for_expected_json(self, respx_mock: MockRouter) -> None:
         class Model(BaseModel):
@@ -1782,6 +1793,17 @@ class Model(BaseModel):
 
         assert isinstance(exc.value.__cause__, ValidationError)
 
+    async def test_client_max_retries_validation(self) -> None:
+        with pytest.raises(TypeError, match=r"max_retries cannot be None"):
+            AsyncFinch(
+                base_url=base_url,
+                access_token=access_token,
+                client_id=client_id,
+                client_secret=client_secret,
+                _strict_response_validation=True,
+                max_retries=cast(Any, None),
+            )
+
     @pytest.mark.respx(base_url=base_url)
     @pytest.mark.asyncio
     async def test_received_text_for_expected_json(self, respx_mock: MockRouter) -> None: