diff --git a/lib/pleroma/user.ex b/lib/pleroma/user.ex
index 5e10ac25f..64b69e686 100644
--- a/lib/pleroma/user.ex
+++ b/lib/pleroma/user.ex
@@ -174,11 +174,25 @@ def following_count(%User{} = user) do
     |> Repo.aggregate(:count, :id)
   end
 
+  defp truncate_if_exists(params, key, max_length) do
+    if Map.has_key?(params, key) and is_binary(params[key]) do
+      {value, _chopped} = String.split_at(params[key], max_length)
+      Map.put(params, key, value)
+    else
+      params
+    end
+  end
+
   def remote_user_creation(params) do
     bio_limit = Pleroma.Config.get([:instance, :user_bio_length], 5000)
     name_limit = Pleroma.Config.get([:instance, :user_name_length], 100)
 
-    params = Map.put(params, :info, params[:info] || %{})
+    params =
+      params
+      |> Map.put(:info, params[:info] || %{})
+      |> truncate_if_exists(:name, name_limit)
+      |> truncate_if_exists(:bio, bio_limit)
+
     info_cng = User.Info.remote_user_creation(%User.Info{}, params[:info])
 
     changes =
diff --git a/lib/pleroma/user/info.ex b/lib/pleroma/user/info.ex
index 779bfbc18..151e025de 100644
--- a/lib/pleroma/user/info.ex
+++ b/lib/pleroma/user/info.ex
@@ -242,6 +242,13 @@ def set_keys(info, keys) do
   end
 
   def remote_user_creation(info, params) do
+    params =
+      if Map.has_key?(params, :fields) do
+        Map.put(params, :fields, Enum.map(params[:fields], &truncate_field/1))
+      else
+        params
+      end
+
     info
     |> cast(params, [
       :ap_enabled,
@@ -326,6 +333,16 @@ defp valid_field?(%{"name" => name, "value" => value}) do
 
   defp valid_field?(_), do: false
 
+  defp truncate_field(%{"name" => name, "value" => value}) do
+    {name, _chopped} =
+      String.split_at(name, Pleroma.Config.get([:instance, :account_field_name_length], 255))
+
+    {value, _chopped} =
+      String.split_at(value, Pleroma.Config.get([:instance, :account_field_value_length], 255))
+
+    %{"name" => name, "value" => value}
+  end
+
   @spec confirmation_changeset(Info.t(), keyword()) :: Changeset.t()
   def confirmation_changeset(info, opts) do
     need_confirmation? = Keyword.get(opts, :need_confirmation)
diff --git a/test/user_test.exs b/test/user_test.exs
index 05b158025..4d79f858a 100644
--- a/test/user_test.exs
+++ b/test/user_test.exs
@@ -570,22 +570,6 @@ test "it has required fields" do
         refute cs.valid?
       end)
     end
-
-    test "it restricts some sizes" do
-      bio_limit = Pleroma.Config.get([:instance, :user_bio_length], 5000)
-      name_limit = Pleroma.Config.get([:instance, :user_name_length], 100)
-
-      [bio: bio_limit, name: name_limit]
-      |> Enum.each(fn {field, size} ->
-        string = String.pad_leading(".", size)
-        cs = User.remote_user_creation(Map.put(@valid_remote, field, string))
-        assert cs.valid?
-
-        string = String.pad_leading(".", size + 1)
-        cs = User.remote_user_creation(Map.put(@valid_remote, field, string))
-        refute cs.valid?
-      end)
-    end
   end
 
   describe "followers and friends" do
@@ -1117,11 +1101,60 @@ test "get_public_key_for_ap_id fetches a user that's not in the db" do
     assert {:ok, _key} = User.get_public_key_for_ap_id("http://mastodon.example.org/users/admin")
   end
 
-  test "insert or update a user from given data" do
-    user = insert(:user, %{nickname: "nick@name.de"})
-    data = %{ap_id: user.ap_id <> "xxx", name: user.name, nickname: user.nickname}
+  describe "insert or update a user from given data" do
+    test "with normal data" do
+      user = insert(:user, %{nickname: "nick@name.de"})
+      data = %{ap_id: user.ap_id <> "xxx", name: user.name, nickname: user.nickname}
 
-    assert {:ok, %User{}} = User.insert_or_update_user(data)
+      assert {:ok, %User{}} = User.insert_or_update_user(data)
+    end
+
+    test "with overly long fields" do
+      current_max_length = Pleroma.Config.get([:instance, :account_field_value_length], 255)
+      user = insert(:user, nickname: "nickname@supergood.domain")
+
+      data = %{
+        ap_id: user.ap_id,
+        name: user.name,
+        nickname: user.nickname,
+        info: %{
+          fields: [
+            %{"name" => "myfield", "value" => String.duplicate("h", current_max_length + 1)}
+          ]
+        }
+      }
+
+      assert {:ok, %User{}} = User.insert_or_update_user(data)
+    end
+
+    test "with an overly long bio" do
+      current_max_length = Pleroma.Config.get([:instance, :user_bio_length], 5000)
+      user = insert(:user, nickname: "nickname@supergood.domain")
+
+      data = %{
+        ap_id: user.ap_id,
+        name: user.name,
+        nickname: user.nickname,
+        bio: String.duplicate("h", current_max_length + 1),
+        info: %{}
+      }
+
+      assert {:ok, %User{}} = User.insert_or_update_user(data)
+    end
+
+    test "with an overly long display name" do
+      current_max_length = Pleroma.Config.get([:instance, :user_name_length], 100)
+      user = insert(:user, nickname: "nickname@supergood.domain")
+
+      data = %{
+        ap_id: user.ap_id,
+        name: String.duplicate("h", current_max_length + 1),
+        nickname: user.nickname,
+        info: %{}
+      }
+
+      assert {:ok, %User{}} = User.insert_or_update_user(data)
+    end
   end
 
   describe "per-user rich-text filtering" do