diff --git a/custom_components/openai_compatible/__init__.py b/custom_components/openai_compatible/__init__.py
index 459338a..f7de9bc 100644
--- a/custom_components/openai_compatible/__init__.py
+++ b/custom_components/openai_compatible/__init__.py
@@ -49,6 +49,7 @@ from .const import (
     CONF_TEMPERATURE,
     CONF_TOP_P,
     DEFAULT_AI_TASK_NAME,
+    DEFAULT_BASE_URL,
     DEFAULT_NAME,
     DEFAULT_STT_NAME,
     DEFAULT_TTS_NAME,
@@ -489,6 +490,16 @@ async def async_migrate_entry(hass: HomeAssistant, entry: OpenAIConfigEntry) ->
                     )
         hass.config_entries.async_update_entry(entry, minor_version=7)
 
+    if entry.version == 2 and entry.minor_version == 7:
+        # base_url is this fork's addition, so an entry written by a build
+        # from before it existed has no such key, and async_setup_entry's
+        # lookup raises KeyError. Such an install was implicitly talking to
+        # OpenAI, which is what DEFAULT_BASE_URL is, so backfilling it keeps
+        # the endpoint it was already using.
+        data = dict(entry.data)
+        data.setdefault(CONF_BASE_URL, DEFAULT_BASE_URL)
+        hass.config_entries.async_update_entry(entry, data=data, minor_version=8)
+
     LOGGER.debug(
         "Migration to version %s:%s successful", entry.version, entry.minor_version
     )
diff --git a/custom_components/openai_compatible/config_flow.py b/custom_components/openai_compatible/config_flow.py
index 06575ab..4f0df15 100644
--- a/custom_components/openai_compatible/config_flow.py
+++ b/custom_components/openai_compatible/config_flow.py
@@ -134,7 +134,7 @@ class OpenAIConfigFlow(ConfigFlow, domain=DOMAIN):
     """Handle a config flow for OpenAI Conversation."""
 
     VERSION = 2
-    MINOR_VERSION = 7
+    MINOR_VERSION = 8
 
     @override
     async def async_step_user(
diff --git a/tests/test_base_url.py b/tests/test_base_url.py
index 2da5d6a..6824f89 100644
--- a/tests/test_base_url.py
+++ b/tests/test_base_url.py
@@ -5,7 +5,11 @@ from unittest.mock import AsyncMock, patch
 from homeassistant.core import HomeAssistant
 from pytest_homeassistant_custom_component.common import MockConfigEntry
 
-from custom_components.openai_compatible.const import CONF_BASE_URL, DOMAIN
+from custom_components.openai_compatible.const import (
+    CONF_BASE_URL,
+    DEFAULT_BASE_URL,
+    DOMAIN,
+)
 
 
 async def test_client_built_with_base_url(hass: HomeAssistant) -> None:
@@ -48,3 +52,31 @@ async def test_api_key_optional(hass: HomeAssistant) -> None:
         await hass.async_block_till_done()
 
     assert mock_client.call_args.kwargs["api_key"] == "not-required"
+
+
+async def test_migration_backfills_missing_base_url(hass: HomeAssistant) -> None:
+    """An entry stored before base_url existed must still set up.
+
+    Entries written by an earlier build of this fork have no base_url key at
+    all, so anything that indexes entry.data[CONF_BASE_URL] raises KeyError
+    and the integration fails to load on restart.
+    """
+    entry = MockConfigEntry(
+        domain=DOMAIN,
+        data={"api_key": "sk-test"},
+        version=2,
+        minor_version=7,
+    )
+    entry.add_to_hass(hass)
+
+    with patch(
+        "custom_components.openai_compatible.openai.AsyncOpenAI"
+    ) as mock_client:
+        mock_client.return_value.platform_headers = lambda: {}
+        mock_client.return_value.with_options.return_value.models.list = AsyncMock()
+        assert await hass.config_entries.async_setup(entry.entry_id)
+        await hass.async_block_till_done()
+
+    assert entry.data[CONF_BASE_URL] == DEFAULT_BASE_URL
+    assert entry.minor_version == 8
+    assert mock_client.call_args.kwargs["base_url"] == DEFAULT_BASE_URL
diff --git a/tests/test_config_flow.py b/tests/test_config_flow.py
index 9585815..37cc3ee 100644
--- a/tests/test_config_flow.py
+++ b/tests/test_config_flow.py
@@ -122,7 +122,7 @@ async def test_form(hass: HomeAssistant) -> None:
         },
     ]
     assert result2["version"] == 2
-    assert result2["minor_version"] == 7
+    assert result2["minor_version"] == 8
     assert len(mock_setup_entry.mock_calls) == 1