diff --git a/config/emoji.txt b/config/emoji.txt
index 200768ad1..52b714ee5 100644
--- a/config/emoji.txt
+++ b/config/emoji.txt
@@ -1,2 +1,3 @@
 firefox, /emoji/Firefox.gif, Gif,Fun
 blank, /emoji/blank.png, Fun
+dinosaur, /emoji/dino walking.gif, Gif
diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index 565d32433..5499f8a08 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -919,7 +919,7 @@ def add_emoji_tags(object), do: object
 
   defp build_emoji_tag({name, url}) do
     %{
-      "icon" => %{"url" => url, "type" => "Image"},
+      "icon" => %{"url" => "#{URI.encode(url)}", "type" => "Image"},
       "name" => ":" <> name <> ":",
       "type" => "Emoji",
       "updated" => "1970-01-01T00:00:00Z",
diff --git a/priv/static/emoji/dino walking.gif b/priv/static/emoji/dino walking.gif
new file mode 100644
index 000000000..694a541e7
Binary files /dev/null and b/priv/static/emoji/dino walking.gif differ
diff --git a/test/pleroma/web/activity_pub/transmogrifier_test.exs b/test/pleroma/web/activity_pub/transmogrifier_test.exs
index 66ea7664a..aa32ebaab 100644
--- a/test/pleroma/web/activity_pub/transmogrifier_test.exs
+++ b/test/pleroma/web/activity_pub/transmogrifier_test.exs
@@ -281,6 +281,21 @@ test "it can handle Listen activities" do
 
       {:ok, _modified} = Transmogrifier.prepare_outgoing(activity.data)
     end
+
+    test "custom emoji urls are URI encoded" do
+      # :dinosaur: filename has a space -> dino walking.gif
+      user = insert(:user)
+
+      {:ok, activity} = CommonAPI.post(user, %{status: "everybody do the dinosaur :dinosaur:"})
+
+      {:ok, prepared} = Transmogrifier.prepare_outgoing(activity.data)
+
+      assert length(prepared["object"]["tag"]) == 1
+
+      url = prepared["object"]["tag"] |> List.first() |> Map.get("icon") |> Map.get("url")
+
+      assert url == "http://localhost:4001/emoji/dino%20walking.gif"
+    end
   end
 
   describe "user upgrade" do