diff --git a/lib/pleroma/config/deprecation_warnings.ex b/lib/pleroma/config/deprecation_warnings.ex
index 12df7fcf5..954ead142 100644
--- a/lib/pleroma/config/deprecation_warnings.ex
+++ b/lib/pleroma/config/deprecation_warnings.ex
@@ -80,6 +80,44 @@ def check_simple_policy_tuples do
     end
   end
 
+  def check_quarantined_instances_tuples do
+    has_strings =
+      Config.get([:instance, :quarantined_instances]) |> Enum.any?(fn e -> is_binary(e) end)
+
+    if has_strings do
+      Logger.warn("""
+      !!!DEPRECATION WARNING!!!
+      Your config is using strings in the quarantined_instances configuration instead of tuples. They should work for now, but you are advised to change to the new configuration to prevent possible issues later:
+
+      ```
+      config :pleroma, :instance,
+        quarantined_instances: ["instance.tld"]
+      ```
+
+      Is now
+
+
+      ```
+      config :pleroma, :instance,
+        quarantined_instances: [{"instance.tld", "Reason for quarantine"}]
+      ```
+      """)
+
+      new_config =
+        Config.get([:instance, :quarantined_instances])
+        |> Enum.map(fn
+          {instance, reason} -> {instance, reason}
+          instance -> {instance, ""}
+        end)
+
+      Config.put([:instance, :quarantined_instances], new_config)
+
+      :error
+    else
+      :ok
+    end
+  end
+
   def check_hellthread_threshold do
     if Config.get([:mrf_hellthread, :threshold]) do
       Logger.warn("""
@@ -94,13 +132,14 @@ def check_hellthread_threshold do
   end
 
   def warn do
-    with :ok <- check_simple_policy_tuples(),
-         :ok <- check_hellthread_threshold(),
+    with :ok <- check_hellthread_threshold(),
          :ok <- check_old_mrf_config(),
          :ok <- check_media_proxy_whitelist_config(),
          :ok <- check_welcome_message_config(),
          :ok <- check_gun_pool_options(),
-         :ok <- check_activity_expiration_config() do
+         :ok <- check_activity_expiration_config(),
+         :ok <- check_quarantined_instances_tuples(),
+         :ok <- check_simple_policy_tuples() do
       :ok
     else
       _ ->
diff --git a/test/config/deprecation_warnings_test.exs b/test/config/deprecation_warnings_test.exs
index 8233cd9bd..497473ac0 100644
--- a/test/config/deprecation_warnings_test.exs
+++ b/test/config/deprecation_warnings_test.exs
@@ -83,6 +83,56 @@ test "doesn't give a warning with correct config" do
     end
   end
 
+  describe "quarantined_instances tuples" do
+    test "gives warning when there are still strings" do
+      clear_config([:instance, :quarantined_instances], [
+        {"domain.com", "some reason"},
+        "somedomain.tld"
+      ])
+
+      assert capture_log(fn -> DeprecationWarnings.check_quarantined_instances_tuples() end) =~
+               """
+               !!!DEPRECATION WARNING!!!
+               Your config is using strings in the quarantined_instances configuration instead of tuples. They should work for now, but you are advised to change to the new configuration to prevent possible issues later:
+
+               ```
+               config :pleroma, :instance,
+                 quarantined_instances: ["instance.tld"]
+               ```
+
+               Is now
+
+
+               ```
+               config :pleroma, :instance,
+                 quarantined_instances: [{"instance.tld", "Reason for quarantine"}]
+               ```
+               """
+    end
+
+    test "transforms config to tuples" do
+      clear_config([:instance, :quarantined_instances], [
+        {"domain.com", "some reason"},
+        "some.tld"
+      ])
+
+      expected_config = [{"domain.com", "some reason"}, {"some.tld", ""}]
+
+      capture_log(fn -> DeprecationWarnings.check_quarantined_instances_tuples() end)
+
+      assert Config.get([:instance, :quarantined_instances]) == expected_config
+    end
+
+    test "doesn't give a warning with correct config" do
+      clear_config([:instance, :quarantined_instances], [
+        {"domain.com", "some reason"},
+        {"some.tld", ""}
+      ])
+
+      assert capture_log(fn -> DeprecationWarnings.check_quarantined_instances_tuples() end) == ""
+    end
+  end
+
   test "check_old_mrf_config/0" do
     clear_config([:instance, :rewrite_policy], Pleroma.Web.ActivityPub.MRF.NoOpPolicy)
     clear_config([:instance, :mrf_transparency], true)