diff --git a/routes/note_routes.py b/routes/note_routes.py
index 3d356f5c9..ec8d14925 100644
--- a/routes/note_routes.py
+++ b/routes/note_routes.py
@@ -479,7 +479,9 @@ async def dispatch_reminder(
                 base = intg["base_url"].rstrip("/")
                 topic = settings.get("reminder_ntfy_topic") or "reminders"
                 ntfy_body = synthesis or note_body or title
-                hdrs = {"Title": title or "Reminder", "Priority": "high", "Tags": "bell"}
+                # ntfy Title is an ASCII HTTP header; sanitize Unicode and cap its length.
+                _clean_title = (title or "Reminder").encode("ascii", "replace").decode("ascii")[:200]
+                hdrs = {"Title": _clean_title, "Priority": "high", "Tags": "bell"}
                 api_key = intg.get("api_key", "")
                 if api_key:
                     hdrs["Authorization"] = f"Bearer {api_key}"