diff --git a/lib/pleroma/web/activity_pub/mrf.ex b/lib/pleroma/web/activity_pub/mrf.ex
index ac00fa54b..5ac4f9f20 100644
--- a/lib/pleroma/web/activity_pub/mrf.ex
+++ b/lib/pleroma/web/activity_pub/mrf.ex
@@ -100,6 +100,11 @@ def subdomain_match?(domains, host) do
     Enum.any?(domains, fn domain -> Regex.match?(domain, host) end)
   end
 
+  @spec instance_list_from_tuples([{String.t(), String.t()}]) :: [String.t()]
+  def instance_list_from_tuples(list) do
+    Enum.map(list, fn {instance, _} -> instance end)
+  end
+
   def describe(policies) do
     {:ok, policy_configs} =
       policies
diff --git a/lib/pleroma/web/activity_pub/mrf/simple_policy.ex b/lib/pleroma/web/activity_pub/mrf/simple_policy.ex
index 8ef03aa3a..fe0dc874b 100644
--- a/lib/pleroma/web/activity_pub/mrf/simple_policy.ex
+++ b/lib/pleroma/web/activity_pub/mrf/simple_policy.ex
@@ -187,9 +187,7 @@ defp check_object(object), do: {:ok, object}
 
   defp instance_list(config_key) do
     Config.get([:mrf_simple, config_key])
-    |> Enum.map(fn
-      {instance, _} -> instance
-    end)
+    |> MRF.instance_list_from_tuples()
   end
 
   @impl true
diff --git a/lib/pleroma/web/activity_pub/publisher.ex b/lib/pleroma/web/activity_pub/publisher.ex
index 590beef64..4f29a4411 100644
--- a/lib/pleroma/web/activity_pub/publisher.ex
+++ b/lib/pleroma/web/activity_pub/publisher.ex
@@ -112,6 +112,7 @@ defp should_federate?(inbox, public) do
 
       quarantined_instances =
         Config.get([:instance, :quarantined_instances], [])
+        |> Pleroma.Web.ActivityPub.MRF.instance_list_from_tuples()
         |> Pleroma.Web.ActivityPub.MRF.subdomains_regex()
 
       !Pleroma.Web.ActivityPub.MRF.subdomain_match?(quarantined_instances, host)
diff --git a/test/pleroma/web/activity_pub/mrf_test.exs b/test/pleroma/web/activity_pub/mrf_test.exs
index 61d308b97..6ab27bc86 100644
--- a/test/pleroma/web/activity_pub/mrf_test.exs
+++ b/test/pleroma/web/activity_pub/mrf_test.exs
@@ -63,6 +63,15 @@ test "matches are case-insensitive" do
     end
   end
 
+  describe "instance_list_from_tuples/1" do
+    test "returns a list of instances from a list of {instance, reason} tuples" do
+      list = [{"some.tld", "a reason"}, {"other.tld", "another reason"}]
+      expected = ["some.tld", "other.tld"]
+
+      assert MRF.instance_list_from_tuples(list) == expected
+    end
+  end
+
   describe "describe/0" do
     test "it works as expected with noop policy" do
       clear_config([:mrf, :policies], [Pleroma.Web.ActivityPub.MRF.NoOpPolicy])
diff --git a/test/pleroma/web/activity_pub/publisher_test.exs b/test/pleroma/web/activity_pub/publisher_test.exs
index d0bb43fb2..b50e22bbe 100644
--- a/test/pleroma/web/activity_pub/publisher_test.exs
+++ b/test/pleroma/web/activity_pub/publisher_test.exs
@@ -271,7 +271,7 @@ test "publish to url with with different ports" do
                    Pleroma.Web.Federator.Publisher,
                    [:passthrough],
                    [] do
-      Config.put([:instance, :quarantined_instances], ["domain.com"])
+      Config.put([:instance, :quarantined_instances], [{"domain.com", "some reason"}])
 
       follower =
         insert(:user, %{
@@ -308,7 +308,7 @@ test "publish to url with with different ports" do
                    Pleroma.Web.Federator.Publisher,
                    [:passthrough],
                    [] do
-      Config.put([:instance, :quarantined_instances], ["somedomain.com"])
+      Config.put([:instance, :quarantined_instances], [{"somedomain.com", "some reason"}])
 
       follower =
         insert(:user, %{