diff --git a/app/serializers/node_info/serializer.rb b/app/serializers/node_info/serializer.rb
index 56f5280698..bdf1ca884d 100644
--- a/app/serializers/node_info/serializer.rb
+++ b/app/serializers/node_info/serializer.rb
@@ -43,6 +43,10 @@ class NodeInfo::Serializer < ActiveModel::Serializer
       nodeName: Setting.site_title,
       nodeDescription: Setting.site_short_description,
       features: capabilities_for_nodeinfo,
+      upstream: {
+        name: 'Mastodon',
+        version: Mastodon::Version.to_s_of_mastodon,
+      },
     }
   end
 
diff --git a/lib/mastodon/version.rb b/lib/mastodon/version.rb
index 1c9bee3a21..7f6ada0f44 100644
--- a/lib/mastodon/version.rb
+++ b/lib/mastodon/version.rb
@@ -46,8 +46,19 @@ module Mastodon
       components.join
     end
 
+    def to_s_of_mastodon
+      components = [to_a.join('.')]
+      components << "-#{prerelease}" if prerelease.present?
+      components << "+#{build_metadata_of_mastodon}" if build_metadata_of_mastodon.present?
+      components.join
+    end
+
     def build_metadata
-      ['kmyblue', to_s_of_kmyblue, ENV.fetch('MASTODON_VERSION_METADATA', nil)].compact.join('.')
+      ['kmyblue', to_s_of_kmyblue, build_metadata_of_mastodon].compact.join('.')
+    end
+
+    def build_metadata_of_mastodon
+      ENV.fetch('MASTODON_VERSION_METADATA', nil)
     end
 
     def to_a