diff --git a/web/src/subscriber_api.ts b/web/src/subscriber_api.ts
index eb7ebce354..a2936f1201 100644
--- a/web/src/subscriber_api.ts
+++ b/web/src/subscriber_api.ts
@@ -14,20 +14,21 @@ export function add_user_ids_to_stream(
     sub: StreamSubscription,
     success: () => void,
     failure: (xhr: JQuery.jqXHR<unknown>) => void,
-): JQuery.jqXHR<unknown> | undefined {
+): void {
     // TODO: use stream_id when backend supports it
     const stream_name = sub.name;
     if (user_ids.length === 1 && people.is_my_user_id(Number(user_ids[0]))) {
         // Self subscribe
         const color = sub.color;
-        return channel.post({
+        void channel.post({
             url: "/json/users/me/subscriptions",
             data: {subscriptions: JSON.stringify([{name: stream_name, color}])},
             success,
             error: failure,
         });
+        return;
     }
-    return channel.post({
+    void channel.post({
         url: "/json/users/me/subscriptions",
         data: {
             subscriptions: JSON.stringify([{name: stream_name}]),
@@ -43,10 +44,10 @@ export function remove_user_id_from_stream(
     sub: StreamSubscription,
     success: () => void,
     failure: (xhr: JQuery.jqXHR<unknown>) => void,
-): JQuery.jqXHR<unknown> | undefined {
+): void {
     // TODO: use stream_id when backend supports it
     const stream_name = sub.name;
-    return channel.del({
+    void channel.del({
         url: "/json/users/me/subscriptions",
         data: {subscriptions: JSON.stringify([stream_name]), principals: JSON.stringify([user_id])},
         success,