diff --git a/test/aprsme/cluster/packet_distributor_test.exs b/test/aprsme/cluster/packet_distributor_test.exs
index 76899c7..b2c5db6 100644
--- a/test/aprsme/cluster/packet_distributor_test.exs
+++ b/test/aprsme/cluster/packet_distributor_test.exs
@@ -88,4 +88,31 @@ defmodule Aprsme.Cluster.PacketDistributorTest do
       assert result == :ok
     end
   end
+
+  describe "GenServer callbacks" do
+    test "init/1 subscribes to the topic and returns empty state" do
+      assert {:ok, %{}} = PacketDistributor.init([])
+      # Callback subscribes the caller to cluster:packets.
+      Phoenix.PubSub.broadcast(Aprsme.PubSub, "cluster:packets", :ping)
+      assert_receive :ping, 100
+    end
+
+    test "handle_info forwards distributed packets" do
+      state = %{}
+
+      assert {:noreply, ^state} =
+               PacketDistributor.handle_info({:distributed_packet, @test_packet}, state)
+    end
+
+    test "terminate/2 unsubscribes from the topic and returns :ok" do
+      # Subscribe first so we have something to unsubscribe.
+      PacketDistributor.subscribe()
+      assert :ok = PacketDistributor.terminate(:shutdown, %{})
+
+      # After terminate, this process should no longer receive cluster:packets
+      # broadcasts.
+      Phoenix.PubSub.broadcast(Aprsme.PubSub, "cluster:packets", :should_not_arrive)
+      refute_receive :should_not_arrive, 100
+    end
+  end
 end