diff --git a/src/llm/backends/gemini.py b/src/llm/backends/gemini.py
index 5194f6a4..e0531d38 100644
--- a/src/llm/backends/gemini.py
+++ b/src/llm/backends/gemini.py
@@ -321,7 +321,7 @@ class GeminiBackend:
         if timeout is not None:
             if http_options is None:
                 http_options = genai_types.HttpOptions()
-            http_options.timeout = timeout
+            http_options.timeout = int(timeout * 1000)
         if http_options is not None:
             config["http_options"] = http_options
         return config
diff --git a/tests/llm/test_backends/test_gemini.py b/tests/llm/test_backends/test_gemini.py
index 0cebdb59..8295ab26 100644
--- a/tests/llm/test_backends/test_gemini.py
+++ b/tests/llm/test_backends/test_gemini.py
@@ -129,7 +129,7 @@ async def test_gemini_backend_maps_timeout_to_http_options() -> None:
     await_args = client.aio.models.generate_content.await_args
     if await_args is None:
         raise AssertionError("Expected Gemini generate_content call")
-    assert await_args.kwargs["config"]["http_options"].timeout == 90.0
+    assert await_args.kwargs["config"]["http_options"].timeout == 90_000
 
 
 @pytest.mark.asyncio