diff --git a/pretix_matrix_inviter/tasks.py b/pretix_matrix_inviter/tasks.py
index 0756c20341ca7ad4bc3740de0edbe72b25e9d597..8b45ef05ff2fd40de3f30e76679eaac19b6b4b00 100644
--- a/pretix_matrix_inviter/tasks.py
+++ b/pretix_matrix_inviter/tasks.py
@@ -4,6 +4,7 @@ from celery.exceptions import MaxRetriesExceededError
 from pretix.base.models import Event, Order, OrderPosition
 from pretix.base.services.tasks import TransactionAwareTask
 from pretix.celery_app import app
+from urllib.parse import quote as url_quote
 
 logger = logging.getLogger(__name__)
 
@@ -37,8 +38,8 @@ def matrix_inviter_invite(
     try:
         r = requests.post(
             "https://{}/_matrix/client/v3/rooms/{}/invite".format(
-                event.settings.matrix_inviter_matrix_server,
-                room_matrix_id,
+                url_quote(event.settings.matrix_inviter_matrix_server),
+                url_quote(room_matrix_id),
             ),
             headers={
                 "Authorization": "Bearer {}".format(