diff --git a/replicate/client.py b/replicate/client.py
index 73c9dd2d..19753c2b 100644
--- a/replicate/client.py
+++ b/replicate/client.py
@@ -26,6 +26,8 @@
 class Client:
     """A Replicate API client library"""
 
+    __client: Optional[httpx.Client] = None
+
     def __init__(
         self,
         api_token: Optional[str] = None,
@@ -36,37 +38,41 @@ def __init__(
     ) -> None:
         super().__init__()
 
-        api_token = api_token or os.environ.get("REPLICATE_API_TOKEN")
-
-        base_url = base_url or os.environ.get(
-            "REPLICATE_API_BASE_URL", "https://api.replicate.com"
+        self._api_token = api_token
+        self._base_url = (
+            base_url
+            or os.environ.get("REPLICATE_API_BASE_URL")
+            or "https://api.replicate.com"
         )
-
-        timeout = timeout or httpx.Timeout(
+        self._timeout = timeout or httpx.Timeout(
             5.0, read=30.0, write=30.0, connect=5.0, pool=10.0
         )
+        self._transport = kwargs.pop("transport", httpx.HTTPTransport())
+        self._client_kwargs = kwargs
 
         self.poll_interval = float(os.environ.get("REPLICATE_POLL_INTERVAL", "0.5"))
 
-        headers = {
-            "User-Agent": f"replicate-python/{__version__}",
-        }
-
-        if api_token is not None and api_token != "":
-            headers["Authorization"] = f"Token {api_token}"
-
-        transport = kwargs.pop("transport", httpx.HTTPTransport())
-
-        self._client = self._build_client(
-            **kwargs,
-            base_url=base_url,
-            headers=headers,
-            timeout=timeout,
-            transport=RetryTransport(wrapped_transport=transport),
-        )
+    @property
+    def _client(self) -> httpx.Client:
+        if self.__client is None:
+            headers = {
+                "User-Agent": f"replicate-python/{__version__}",
+            }
+
+            api_token = self._api_token or os.environ.get("REPLICATE_API_TOKEN")
+
+            if api_token is not None and api_token != "":
+                headers["Authorization"] = f"Token {api_token}"
+
+            self.__client = httpx.Client(
+                **self._client_kwargs,
+                base_url=self._base_url,
+                headers=headers,
+                timeout=self._timeout,
+                transport=RetryTransport(wrapped_transport=self._transport),
+            )
 
-    def _build_client(self, **kwargs) -> httpx.Client:
-        return httpx.Client(**kwargs)
+        return self.__client
 
     def _request(self, method: str, path: str, **kwargs) -> httpx.Response:
         resp = self._client.request(method, path, **kwargs)
diff --git a/tests/test_client.py b/tests/test_client.py
new file mode 100644
index 00000000..42cf28da
--- /dev/null
+++ b/tests/test_client.py
@@ -0,0 +1,20 @@
+import os
+from unittest import mock
+
+import httpx
+import pytest
+
+
+@pytest.mark.asyncio
+async def test_authorization_when_setting_environ_after_import():
+    import replicate
+
+    token = "test-set-after-import"  # noqa: S105
+
+    with mock.patch.dict(
+        os.environ,
+        {"REPLICATE_API_TOKEN": token},
+    ):
+        client: httpx.Client = replicate.default_client._client
+        assert "Authorization" in client.headers
+        assert client.headers["Authorization"] == f"Token {token}"