diff --git a/__init__.py b/__init__.py
index 014ffec..1a68806 100644
--- a/__init__.py
+++ b/__init__.py
@@ -34,7 +34,24 @@ def castle_stop():
 def castle_start():
     """Initialize Castle extension background tasks"""
     from lnbits.tasks import create_permanent_unique_task
+    from .fava_client import init_fava_client
+    from .models import CastleSettings
 
+    # Initialize Fava client with default settings
+    # (Will be re-initialized if admin updates settings)
+    defaults = CastleSettings()
+    try:
+        init_fava_client(
+            fava_url=defaults.fava_url,
+            ledger_slug=defaults.fava_ledger_slug,
+            timeout=defaults.fava_timeout
+        )
+        logger.info(f"Fava client initialized: {defaults.fava_url}/{defaults.fava_ledger_slug}")
+    except Exception as e:
+        logger.error(f"Failed to initialize Fava client: {e}")
+        logger.warning("Castle will not function without Fava. Please configure Fava settings.")
+
+    # Start background tasks
     task = create_permanent_unique_task("ext_castle", wait_for_paid_invoices)
     scheduled_tasks.append(task)