diff --git a/app.py b/app.py
index 953637f..f3b765c 100644
--- a/app.py
+++ b/app.py
@@ -271,6 +271,8 @@ def server_host_value(value: Any = None) -> str:
     """Return a non-empty server host string."""
     if value is None:
         value = config_section("server").get("host", "0.0.0.0")
+    if not isinstance(value, str):
+        return "0.0.0.0"
     host = str(value or "").strip()
     return host if host else "0.0.0.0"
 
diff --git a/tests/test_vibe_status.py b/tests/test_vibe_status.py
index 8cdb0fd..f13d11e 100644
--- a/tests/test_vibe_status.py
+++ b/tests/test_vibe_status.py
@@ -461,6 +461,12 @@ def test_settings_config_from_params_normalizes_server_values(self):
         self.assertEqual(updated["server"]["port"], 65535)
         self.assertEqual(updated["server"]["host"], "0.0.0.0")
 
+    def test_server_host_value_rejects_non_string_values(self):
+        self.assertEqual(app.server_host_value(["127.0.0.1"]), "0.0.0.0")
+        self.assertEqual(app.server_host_value({"host": "127.0.0.1"}), "0.0.0.0")
+        self.assertEqual(app.server_host_value(127001), "0.0.0.0")
+        self.assertEqual(app.server_host_value(" 127.0.0.1 "), "127.0.0.1")
+
     def test_parse_settings_form_keeps_blank_host_for_normalization(self):
         base_config = app.merge_configs(app.DEFAULT_CONFIG, {
             "server": {"port": 8080, "host": "127.0.0.1"},