diff --git a/src/subscriptions/client.py b/src/subscriptions/client.py
index d8422cf..4b33394 100644
--- a/src/subscriptions/client.py
+++ b/src/subscriptions/client.py
@@ -1,4 +1,5 @@
 import os
+from urllib.parse import parse_qsl, urlencode, urlsplit, urlunsplit
 
 import httpx
 
@@ -61,6 +62,13 @@ def update_customer(handle: str, data: dict) -> dict:
     return _call("PUT", f"/v1/customer/{handle}", json=data)
 
 
+def _with_query(url: str, **params: str) -> str:
+    parts = urlsplit(url)
+    query = dict(parse_qsl(parts.query))
+    query.update(params)
+    return urlunsplit(parts._replace(query=urlencode(query)))
+
+
 def create_subscription_session(
     plan_handle: str,
     handle: str,
@@ -70,12 +78,13 @@ def create_subscription_session(
     customer_handle: str | None = None,
     create_customer: dict | None = None,
 ) -> str:
+    # CreateSubscription (POST /v1/subscription) n'a pas de champs accept_url/
+    # cancel_url : ils doivent être ajoutés en query string sur le lien
+    # hosted_page_links.payment_info renvoyé, pas dans le body (cf. doc Frisbii).
     body: dict = {
         "plan": plan_handle,
         "signup_method": "link",
         "handle": handle,
-        "accept_url": accept_url,
-        "cancel_url": cancel_url,
     }
     if customer_handle:
         body["customer"] = customer_handle
@@ -84,7 +93,8 @@ def create_subscription_session(
     if no_trial:
         body["no_trial"] = True
     data = _call("POST", "/v1/subscription", json=body)
-    return data["hosted_page_links"]["payment_info"]
+    payment_info = data["hosted_page_links"]["payment_info"]
+    return _with_query(payment_info, accept_url=accept_url, cancel_url=cancel_url)
 
 
 def create_recurring_session(
diff --git a/src/subscriptions/routes.py b/src/subscriptions/routes.py
index c884a2e..4061f7e 100644
--- a/src/subscriptions/routes.py
+++ b/src/subscriptions/routes.py
@@ -148,6 +148,9 @@ def cancel():
 def webhook():
     payload = request.get_json(silent=True) or {}
     if not webhooks.verify_signature(payload, os.getenv("FRISBII_WEBHOOK_SECRET", "")):
+        logger.warning(
+            "Webhook Frisbii : signature invalide (event %s)", payload.get("id")
+        )
         return "", 403
 
     customer = payload.get("customer")
diff --git a/tests/subscriptions/test_client.py b/tests/subscriptions/test_client.py
index 1b20017..0d86150 100644
--- a/tests/subscriptions/test_client.py
+++ b/tests/subscriptions/test_client.py
@@ -43,7 +43,11 @@ def test_create_subscription_session_with_customer_handle(fake_httpx):
         "https://app/ko",
         customer_handle="colibre-1",
     )
-    assert url == "https://checkout.reepay.com/#/sub-1"
+    assert url == (
+        "https://checkout.reepay.com/"
+        "?accept_url=https%3A%2F%2Fapp%2Fok&cancel_url=https%3A%2F%2Fapp%2Fko"
+        "#/sub-1"
+    )
     body = fake_httpx["calls"][0]["json"]
     assert body["plan"] == "plan_simple"
     assert body["handle"] == "abo-1-1"
@@ -51,6 +55,10 @@ def test_create_subscription_session_with_customer_handle(fake_httpx):
     assert body["signup_method"] == "link"
     assert "generate_handle" not in body
     assert "prepare_subscription" not in body
+    # accept_url/cancel_url ne sont pas des champs de CreateSubscription :
+    # Frisbii les ignore silencieusement s'ils sont dans le body.
+    assert "accept_url" not in body
+    assert "cancel_url" not in body
 
 
 def test_create_subscription_session_no_trial(fake_httpx):