diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index 8df3ca7f..2119bfad 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -11,6 +11,10 @@ permissions:
 
 jobs:
   release:
+    # Releases are cut from the upstream repository only. Without this guard the
+    # workflow also runs on forks, where semantic-release rewrites the version in
+    # pyproject.toml, commits to the default branch and attempts a PyPI upload.
+    if: github.repository == 'appium/python-client'
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v7
diff --git a/appium/webdriver/appium_service.py b/appium/webdriver/appium_service.py
index fe34d869..a28bf410 100644
--- a/appium/webdriver/appium_service.py
+++ b/appium/webdriver/appium_service.py
@@ -181,7 +181,8 @@ def is_listening(self) -> bool:
         if not self.is_running:
             return False
 
-        assert self._cmd
+        if not self._cmd:
+            raise AppiumServiceError('Appium service command has not been initialized')
         try:
             return is_service_listening(
                 _make_server_url(self._cmd),
diff --git a/test/unit/webdriver/appium_service_test.py b/test/unit/webdriver/appium_service_test.py
index d0826c8f..466afad4 100644
--- a/test/unit/webdriver/appium_service_test.py
+++ b/test/unit/webdriver/appium_service_test.py
@@ -53,3 +53,17 @@ def advance_time(seconds):
         assert service.is_listening is expected_result
         assert clock.perf_counter.return_value == expected_elapsed
         assert connection.request.call_args_list == [call('HEAD', 'http://127.0.0.1:4723/status')] * expected_requests
+
+    def test_is_listening_raises_error_when_cmd_is_empty(self):
+        service = AppiumService()
+        process = Mock()
+        process.poll.return_value = None
+        service._process = process
+        service._cmd = []
+
+        with pytest.raises(appium_service.AppiumServiceError, match='Appium service command has not been initialized'):
+            _ = service.is_listening
+
+    def test_is_listening_returns_false_when_not_running(self):
+        service = AppiumService()
+        assert service.is_listening is False