diff --git a/lib/mindwendel/brainstormings.ex b/lib/mindwendel/brainstormings.ex
index dc9cff1b..d9a56ff1 100644
--- a/lib/mindwendel/brainstormings.ex
+++ b/lib/mindwendel/brainstormings.ex
@@ -344,12 +344,12 @@ defmodule Mindwendel.Brainstormings do
 
   ## Examples
 
-      iex> subscribe
+      iex> subscribe(3)
       :ok
 
   """
-  def subscribe do
-    Phoenix.PubSub.subscribe(Mindwendel.PubSub, "ideas")
+  def subscribe(brainstorming_id) do
+    Phoenix.PubSub.subscribe(Mindwendel.PubSub, "brainstormings:" <> brainstorming_id)
   end
 
   @doc """
@@ -364,7 +364,7 @@ defmodule Mindwendel.Brainstormings do
   def broadcast({:ok, idea}, event) do
     Phoenix.PubSub.broadcast(
       Mindwendel.PubSub,
-      "ideas",
+      "brainstormings:" <> idea.brainstorming_id,
       {event, idea |> Repo.preload([:link, :likes])}
     )
 
diff --git a/lib/mindwendel_web/live/brainstorming_live/show.ex b/lib/mindwendel_web/live/brainstorming_live/show.ex
index d1b4b93e..acfea095 100644
--- a/lib/mindwendel_web/live/brainstorming_live/show.ex
+++ b/lib/mindwendel_web/live/brainstorming_live/show.ex
@@ -7,7 +7,7 @@ defmodule MindwendelWeb.BrainstormingLive.Show do
 
   @impl true
   def mount(%{"id" => id}, session, socket) do
-    if connected?(socket), do: Brainstormings.subscribe()
+    if connected?(socket), do: Brainstormings.subscribe(id)
 
     current_user_id = MindwendelService.SessionService.get_current_user_id(session)
 
diff --git a/test/mindwendel/brainstormings_test.exs b/test/mindwendel/brainstormings_test.exs
index c401e933..251bd62f 100644
--- a/test/mindwendel/brainstormings_test.exs
+++ b/test/mindwendel/brainstormings_test.exs
@@ -4,9 +4,12 @@ defmodule Mindwendel.BrainstormingsTest do
   alias Mindwendel.Brainstormings
 
   setup do
+    brainstorming = Factory.insert!(:brainstorming)
+
     %{
-      brainstorming: Factory.insert!(:brainstorming),
-      idea: Factory.insert!(:idea),
+      brainstorming: brainstorming,
+      idea:
+        Factory.insert!(:idea, brainstorming: brainstorming, inserted_at: ~N[2021-01-01 15:04:30]),
       user: Factory.insert!(:user),
       like: Factory.insert!(:like, :with_idea_and_user)
     }
@@ -28,7 +31,7 @@ defmodule Mindwendel.BrainstormingsTest do
   end
 
   describe "list_ideas_for_brainstorming" do
-    test "orders by like count", %{brainstorming: brainstorming, user: user} do
+    test "orders by like count", %{brainstorming: brainstorming, user: user, idea: idea} do
       first_idea = Factory.insert!(:idea, brainstorming_id: brainstorming.id)
       third_idea = Factory.insert!(:idea, brainstorming_id: brainstorming.id)
       second_idea = Factory.insert!(:idea, brainstorming_id: brainstorming.id)
@@ -42,10 +45,14 @@ defmodule Mindwendel.BrainstormingsTest do
       ids =
         Enum.map(Brainstormings.list_ideas_for_brainstorming(brainstorming.id), fn x -> x.id end)
 
-      assert ids == [first_idea.id, second_idea.id, third_idea.id]
+      assert ids == [first_idea.id, second_idea.id, third_idea.id, idea.id]
     end
 
-    test "orders by date if like count is equal", %{brainstorming: brainstorming, user: user} do
+    test "orders by date if like count is equal", %{
+      brainstorming: brainstorming,
+      user: user,
+      idea: idea
+    } do
       older_idea =
         Factory.insert!(:idea,
           brainstorming_id: brainstorming.id,
@@ -64,7 +71,7 @@ defmodule Mindwendel.BrainstormingsTest do
       ids =
         Enum.map(Brainstormings.list_ideas_for_brainstorming(brainstorming.id), fn x -> x.id end)
 
-      assert ids == [younger_idea.id, older_idea.id]
+      assert ids == [younger_idea.id, older_idea.id, idea.id]
     end
   end
 
diff --git a/test/mindwendel_web/channels/brainstorming_channel_test.exs b/test/mindwendel_web/channels/brainstorming_channel_test.exs
new file mode 100644
index 00000000..bd0fcaa6
--- /dev/null
+++ b/test/mindwendel_web/channels/brainstorming_channel_test.exs
@@ -0,0 +1,32 @@
+defmodule MindwendelWeb.BrainstormingChannelTest do
+  use MindwendelWeb.ChannelCase
+
+  alias Mindwendel.Factory
+  alias Mindwendel.Brainstormings
+  alias Mindwendel.Brainstormings.Idea
+
+  setup do
+    %{
+      brainstorming: Factory.insert!(:brainstorming)
+    }
+  end
+
+  describe "subscribe" do
+    test "listening for the brainstorming gets updates for ideas", %{brainstorming: brainstorming} do
+      idea = Factory.insert!(:idea, brainstorming: brainstorming)
+
+      Brainstormings.subscribe(brainstorming.id)
+      Brainstormings.update_idea(idea, %{body: "lalala"})
+      assert_received {:idea_updated, idea}
+    end
+
+    test "does not receive messages from other brainstormings", %{brainstorming: brainstorming} do
+      idea = Factory.insert!(:idea, brainstorming: brainstorming)
+      other_brainstorming = Factory.insert!(:brainstorming)
+
+      Brainstormings.subscribe(other_brainstorming.id)
+      Brainstormings.update_idea(idea, %{body: "lalala"})
+      refute_received {:idea_updated, idea}
+    end
+  end
+end
diff --git a/test/support/factory.ex b/test/support/factory.ex
index 7fc4eb99..a5ff56bf 100644
--- a/test/support/factory.ex
+++ b/test/support/factory.ex
@@ -40,7 +40,7 @@ defmodule Mindwendel.Factory do
   def build(:like, :with_idea_and_user) do
     %Like{
       user: build(:user),
-      idea: build(:idea)
+      idea: build(:idea, brainstorming: build(:brainstorming))
     }
   end