diff --git a/strix/interface/main.py b/strix/interface/main.py
index 18f9113d..5b23d257 100644
--- a/strix/interface/main.py
+++ b/strix/interface/main.py
@@ -169,6 +169,7 @@ async def warm_up_llm() -> None:
                 model_name=dedupe_model,
                 extra_headers=settings.dedupe.extra_headers,
                 timeout=llm.preflight_timeout,
+                api_base_setting="DEDUPE_LLM_API_BASE",
             )
             logger.info("LLM warm-up succeeded for dedupe model %s", dedupe_model)
 
diff --git a/strix/interface/scan_setup.py b/strix/interface/scan_setup.py
index d7d0aab6..0af126d0 100644
--- a/strix/interface/scan_setup.py
+++ b/strix/interface/scan_setup.py
@@ -117,6 +117,7 @@ async def preflight_model_connection(
         model_name=model_name,
         extra_headers=resolved_settings.llm.extra_headers,
         timeout=resolved_settings.llm.preflight_timeout,
+        api_base_setting="LLM_API_BASE",
     )
 
 
@@ -126,8 +127,13 @@ async def preflight_request(
     model_name: str,
     extra_headers: dict[str, str] | None,
     timeout: int,
+    api_base_setting: str,
 ) -> None:
-    """Send one tiny request to ``model`` and fail if it does not answer in ``timeout`` seconds."""
+    """Send one tiny request to ``model`` and fail if it does not answer in ``timeout`` seconds.
+
+    ``api_base_setting`` names the environment variable that points at this
+    model's endpoint, so the timeout message sends the user to the right one.
+    """
     from agents.models.interface import ModelTracing
 
     from strix.core.inputs import make_model_settings
@@ -158,8 +164,8 @@ async def preflight_request(
         )
     except TimeoutError:
         raise TimeoutError(
-            f"{model_name} did not answer within {timeout}s "
-            "(LLM_PREFLIGHT_TIMEOUT). Check LLM_API_BASE and that the endpoint is reachable."
+            f"{model_name} did not answer within {timeout}s (LLM_PREFLIGHT_TIMEOUT). "
+            f"Check {api_base_setting} and that the endpoint is reachable."
         ) from None
 
 
diff --git a/tests/test_preflight_timeout.py b/tests/test_preflight_timeout.py
index 28f40b3f..eb0209de 100644
--- a/tests/test_preflight_timeout.py
+++ b/tests/test_preflight_timeout.py
@@ -8,6 +8,7 @@ from typing import TYPE_CHECKING, Any
 
 import pytest
 
+import strix.interface.main as cli_main
 from strix.config import load_settings, loader
 from strix.interface import scan_setup
 from strix.interface.scan_setup import preflight_model_connection, preflight_request
@@ -56,12 +57,14 @@ def test_preflight_request_fails_after_its_own_timeout_with_a_clear_message() ->
                 model_name="openai/gpt-4o",
                 extra_headers=None,
                 timeout=1,
+                api_base_setting="DEDUPE_LLM_API_BASE",
             )
         )
     assert time.monotonic() - started < 5
     message = str(excinfo.value)
     assert "openai/gpt-4o did not answer within 1s" in message
     assert "LLM_PREFLIGHT_TIMEOUT" in message
+    assert "Check DEDUPE_LLM_API_BASE" in message
     assert model.request_timeouts == [1]
 
 
@@ -82,3 +85,43 @@ def test_preflight_model_connection_uses_the_preflight_timeout(
     asyncio.run(preflight_model_connection("openai/gpt-4o", settings=load_settings()))
     assert seen["timeout"] == 12
     assert seen["model_name"] == "openai/gpt-4o"
+    assert seen["api_base_setting"] == "LLM_API_BASE"
+
+
+def test_warm_up_checks_the_dedupe_model_with_its_own_headers_and_the_preflight_timeout(
+    monkeypatch: pytest.MonkeyPatch, tmp_path: Path
+) -> None:
+    monkeypatch.setenv("STRIX_LLM", "openai/gpt-4o")
+    monkeypatch.setenv("LLM_API_KEY", "sk-test")
+    monkeypatch.setenv("LLM_EXTRA_HEADERS", '{"X-Main": "1"}')
+    monkeypatch.setenv("LLM_TIMEOUT", "600")
+    monkeypatch.setenv("LLM_PREFLIGHT_TIMEOUT", "9")
+    monkeypatch.setenv("STRIX_DEDUPE_MODEL", "anthropic/claude-sonnet-4-5")
+    monkeypatch.setenv("DEDUPE_LLM_EXTRA_HEADERS", '{"X-Dedupe": "1"}')
+    _fresh_settings(monkeypatch, tmp_path)
+
+    dedupe_model = object()
+    calls: list[tuple[object, dict[str, Any]]] = []
+
+    async def record(model: Any, **kwargs: Any) -> None:
+        calls.append((model, kwargs))
+
+    monkeypatch.setattr(scan_setup, "preflight_request", record)
+    monkeypatch.setattr(cli_main, "preflight_request", record)
+    monkeypatch.setattr(
+        "strix.report.dedupe.resolve_dedupe_model", lambda _dedupe, _name: dedupe_model
+    )
+
+    asyncio.run(cli_main.warm_up_llm())
+
+    assert [kwargs["model_name"] for _, kwargs in calls] == [
+        "openai/gpt-4o",
+        "anthropic/claude-sonnet-4-5",
+    ]
+    assert [kwargs["timeout"] for _, kwargs in calls] == [9, 9]
+    assert [kwargs["extra_headers"] for _, kwargs in calls] == [{"X-Main": "1"}, {"X-Dedupe": "1"}]
+    assert [kwargs["api_base_setting"] for _, kwargs in calls] == [
+        "LLM_API_BASE",
+        "DEDUPE_LLM_API_BASE",
+    ]
+    assert calls[1][0] is dedupe_model