diff --git a/lib/pleroma/web/activity_pub/mrf/inline_quote_policy.ex b/lib/pleroma/web/activity_pub/mrf/inline_quote_policy.ex
index 7de4935f2..c78675caf 100644
--- a/lib/pleroma/web/activity_pub/mrf/inline_quote_policy.ex
+++ b/lib/pleroma/web/activity_pub/mrf/inline_quote_policy.ex
@@ -10,10 +10,21 @@ defmodule Pleroma.Web.ActivityPub.MRF.InlineQuotePolicy do
     "<span class=\"quote-inline\"><br/><br/>#{prefix}: <a href=\"#{url}\">#{url}</a></span>"
   end
 
+  defp has_inline_quote?(content, quote_url) do
+    cond do
+      # Does the quote URL exist in the content?
+      content =~ quote_url -> true
+      # Does the content already have a .quote-inline span?
+      content =~ "<span class=\"quote-inline\">" -> true
+      # No inline quote found
+      true -> false
+    end
+  end
+
   defp filter_object(%{"quoteUrl" => quote_url} = object) do
     content = object["content"] || ""
 
-    if content =~ quote_url do
+    if has_inline_quote?(content, quote_url) do
       object
     else
       prefix = Pleroma.Config.get([:mrf_inline_quote, :prefix])
diff --git a/test/fixtures/quote_post/fedibird_quote_mismatched.json b/test/fixtures/quote_post/fedibird_quote_mismatched.json
new file mode 100644
index 000000000..8dee5daff
--- /dev/null
+++ b/test/fixtures/quote_post/fedibird_quote_mismatched.json
@@ -0,0 +1,54 @@
+{
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    {
+      "ostatus": "http://ostatus.org#",
+      "atomUri": "ostatus:atomUri",
+      "inReplyToAtomUri": "ostatus:inReplyToAtomUri",
+      "conversation": "ostatus:conversation",
+      "sensitive": "as:sensitive",
+      "toot": "http://joinmastodon.org/ns#",
+      "votersCount": "toot:votersCount",
+      "fedibird": "http://fedibird.com/ns#",
+      "quoteUri": "fedibird:quoteUri",
+      "expiry": "fedibird:expiry"
+    }
+  ],
+  "id": "https://fedibird.com/users/noellabo/statuses/107712183700212249",
+  "type": "Note",
+  "summary": null,
+  "inReplyTo": null,
+  "published": "2022-01-30T15:44:50Z",
+  "url": "https://fedibird.com/@noellabo/107712183700212249",
+  "attributedTo": "https://fedibird.com/users/noellabo",
+  "to": [
+    "https://www.w3.org/ns/activitystreams#Public"
+  ],
+  "cc": [
+    "https://fedibird.com/users/noellabo/followers"
+  ],
+  "sensitive": false,
+  "atomUri": "https://fedibird.com/users/noellabo/statuses/107712183700212249",
+  "inReplyToAtomUri": null,
+  "conversation": "tag:fedibird.com,2022-01-30:objectId=107712183700170473:objectType=Conversation",
+  "context": "https://fedibird.com/contexts/107712183700170473",
+  "quoteUri": "https://unnerv.jp/users/UN_NERV/statuses/107712176849067434",
+  "_misskey_quote": "https://unnerv.jp/users/UN_NERV/statuses/107712176849067434",
+  "_misskey_content": "揺れていたようだ",
+  "content": "<p>揺れていたようだ<span class=\"quote-inline\"><br/>QT: <a class=\"status-url-link\" data-status-account-acct=\"UN_NERV@unnerv.jp\" data-status-id=\"107712177062934465\" href=\"https://unnerv.jp/@UN_NERV/107712176849067434\" rel=\"nofollow noopener noreferrer\" target=\"_blank\"><span class=\"invisible\">https://</span><span class=\"ellipsis\">unnerv.jp/@UN_NERV/10771217684</span><span class=\"invisible\">9067434</span></a></span></p>",
+  "contentMap": {
+    "ja": "<p>揺れていたようだ<span class=\"quote-inline\"><br/>QT: <a class=\"status-url-link\" data-status-account-acct=\"UN_NERV@unnerv.jp\" data-status-id=\"107712177062934465\" href=\"https://unnerv.jp/@UN_NERV/107712176849067434\" rel=\"nofollow noopener noreferrer\" target=\"_blank\"><span class=\"invisible\">https://</span><span class=\"ellipsis\">unnerv.jp/@UN_NERV/10771217684</span><span class=\"invisible\">9067434</span></a></span></p>"
+  },
+  "attachment": [],
+  "tag": [],
+  "replies": {
+    "id": "https://fedibird.com/users/noellabo/statuses/107712183700212249/replies",
+    "type": "Collection",
+    "first": {
+      "type": "CollectionPage",
+      "next": "https://fedibird.com/users/noellabo/statuses/107712183700212249/replies?only_other_accounts=true&page=true",
+      "partOf": "https://fedibird.com/users/noellabo/statuses/107712183700212249/replies",
+      "items": []
+    }
+  }
+}
diff --git a/test/pleroma/web/activity_pub/mrf/inline_quote_policy_test.exs b/test/pleroma/web/activity_pub/mrf/inline_quote_policy_test.exs
index 2291c1dac..44ee91d4b 100644
--- a/test/pleroma/web/activity_pub/mrf/inline_quote_policy_test.exs
+++ b/test/pleroma/web/activity_pub/mrf/inline_quote_policy_test.exs
@@ -72,4 +72,21 @@ defmodule Pleroma.Web.ActivityPub.MRF.InlineQuotePolicyTest do
     {:ok, filtered} = InlineQuotePolicy.filter(activity)
     assert filtered == activity
   end
+
+  test "skips objects which already have an .inline-quote span" do
+    object =
+      File.read!("test/fixtures/quote_post/fedibird_quote_mismatched.json") |> Jason.decode!()
+
+    # Normally the ObjectValidator will fix this before it reaches MRF
+    object = Map.put(object, "quoteUrl", object["quoteUri"])
+
+    activity = %{
+      "type" => "Create",
+      "actor" => "https://fedibird.com/users/noellabo",
+      "object" => object
+    }
+
+    {:ok, filtered} = InlineQuotePolicy.filter(activity)
+    assert filtered == activity
+  end
 end