diff --git a/lib/pleroma/formatter.ex b/lib/pleroma/formatter.ex
index 3e71a3b5f..cf2944c38 100644
--- a/lib/pleroma/formatter.ex
+++ b/lib/pleroma/formatter.ex
@@ -16,7 +16,7 @@ defmodule Pleroma.Formatter do
   def parse_mentions(text) do
     # Modified from https://www.w3.org/TR/html5/forms.html#valid-e-mail-address
     regex =
-      ~r/@[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+@?[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*/u
+      ~r/@[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]*@?[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*/u
 
     Regex.scan(regex, text)
     |> List.flatten()
diff --git a/test/formatter_test.exs b/test/formatter_test.exs
index abbd7ac93..95558089b 100644
--- a/test/formatter_test.exs
+++ b/test/formatter_test.exs
@@ -123,6 +123,35 @@ defmodule Pleroma.FormatterTest do
 
       assert expected_text == Formatter.finalize({subs, text})
     end
+
+    test "gives a replacement for single-character local nicknames" do
+      text = "@o hi"
+      o = insert(:user, %{nickname: "o"})
+
+      mentions = Formatter.parse_mentions(text)
+
+      {subs, text} = Formatter.add_user_links({[], text}, mentions)
+
+      assert length(subs) == 1
+      Enum.each(subs, fn {uuid, _} -> assert String.contains?(text, uuid) end)
+
+      expected_text = "<span><a class='mention' href='#{o.ap_id}'>@<span>o</span></a></span> hi"
+      assert expected_text == Formatter.finalize({subs, text})
+    end
+
+    test "does not give a replacement for single-character local nicknames who don't exist" do
+      text = "@a hi"
+
+      mentions = Formatter.parse_mentions(text)
+
+      {subs, text} = Formatter.add_user_links({[], text}, mentions)
+
+      assert length(subs) == 0
+      Enum.each(subs, fn {uuid, _} -> assert String.contains?(text, uuid) end)
+
+      expected_text = "@a hi"
+      assert expected_text == Formatter.finalize({subs, text})
+    end
   end
 
   describe ".parse_tags" do