diff --git a/app.py b/app.py
index 5c092a4..27783ff 100644
--- a/app.py
+++ b/app.py
@@ -232,6 +232,9 @@ def index():
 		excludes = (request.form.get("excludes") or "").strip()
 		use_ot = request.form.get("use_ot") is not None
 		use_wf = request.form.get("use_wf") is not None
+		# Falls keine Quelle gewählt ist, standardmäßig OpenThesaurus aktivieren
+		if not use_ot and not use_wf:
+			use_ot = True
 
 		# Suchanfrage protokollieren
 		search_params = {