diff --git a/app/serializers/rest/instance_serializer.rb b/app/serializers/rest/instance_serializer.rb
index 19361277a..03dc1ad85 100644
--- a/app/serializers/rest/instance_serializer.rb
+++ b/app/serializers/rest/instance_serializer.rb
@@ -11,12 +11,17 @@ class REST::InstanceSerializer < ActiveModel::Serializer
   include RoutingHelper
 
   attributes :domain, :title, :version, :source_url, :description,
+             :max_toot_chars,
              :usage, :thumbnail, :icon, :languages, :configuration,
              :registrations, :api_versions
 
   has_one :contact, serializer: ContactSerializer
   has_many :rules, serializer: REST::RuleSerializer
 
+  def max_toot_chars
+    StatusLengthValidator::MAX_CHARS
+  end
+
   def thumbnail
     if object.thumbnail
       {
diff --git a/app/serializers/rest/v1/instance_serializer.rb b/app/serializers/rest/v1/instance_serializer.rb
index 7f9f21c5a..c99f1f9c1 100644
--- a/app/serializers/rest/v1/instance_serializer.rb
+++ b/app/serializers/rest/v1/instance_serializer.rb
@@ -4,6 +4,7 @@ class REST::V1::InstanceSerializer < ActiveModel::Serializer
   include RoutingHelper
 
   attributes :uri, :title, :short_description, :description, :email,
+             :max_toot_chars,
              :version, :urls, :stats, :thumbnail,
              :languages, :registrations, :approval_required, :invites_enabled,
              :configuration
@@ -12,6 +13,10 @@ class REST::V1::InstanceSerializer < ActiveModel::Serializer
 
   has_many :rules, serializer: REST::RuleSerializer
 
+  def max_toot_chars
+    StatusLengthValidator::MAX_CHARS
+  end
+
   def uri
     object.domain
   end