diff --git a/app/api/routers/system.py b/app/api/routers/system.py
index 8df2187..323db7e 100644
--- a/app/api/routers/system.py
+++ b/app/api/routers/system.py
@@ -87,7 +87,13 @@ def get_system_status() -> SystemStatusOut:
     except Exception:
         pass
 
-    ollama_ok = _ensure_client()
+    # bool(), because _ensure_client() has three return values, not two: True and
+    # False when Ollama is enabled and reachable/unreachable, and None when
+    # USE_OLLAMA is false - it returns before it ever probes. ollama_connected is
+    # typed bool, so that None failed response_model validation and turned the
+    # whole endpoint into a 500 on exactly the configuration this deployment
+    # runs (USE_OLLAMA=false). "Ollama is switched off" is not a server error.
+    ollama_ok = bool(_ensure_client())
     dist_ok = FRONTEND_DIST.exists() and (FRONTEND_DIST / "index.html").exists()
 
     return SystemStatusOut(