diff --git a/lib/pleroma/web/activity_pub/mrf.ex b/lib/pleroma/web/activity_pub/mrf.ex
index bd6f6777f..89037ade7 100644
--- a/lib/pleroma/web/activity_pub/mrf.ex
+++ b/lib/pleroma/web/activity_pub/mrf.ex
@@ -104,7 +104,10 @@ defmodule Pleroma.Web.ActivityPub.MRF do
 
   @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)
+    Enum.map(list, fn
+      {instance, _} -> instance
+      instance when is_binary(instance) -> instance
+    end)
   end
 
   def describe(policies) do
diff --git a/test/pleroma/web/activity_pub/mrf_test.exs b/test/pleroma/web/activity_pub/mrf_test.exs
index 6ab27bc86..fd88435ff 100644
--- a/test/pleroma/web/activity_pub/mrf_test.exs
+++ b/test/pleroma/web/activity_pub/mrf_test.exs
@@ -70,6 +70,13 @@ defmodule Pleroma.Web.ActivityPub.MRFTest do
 
       assert MRF.instance_list_from_tuples(list) == expected
     end
+
+    test "it handles legacy config" do
+      list = [{"some.tld", "a reason"}, "other.tld"]
+      expected = ["some.tld", "other.tld"]
+
+      assert MRF.instance_list_from_tuples(list) == expected
+    end
   end
 
   describe "describe/0" do