diff --git a/CHANGELOG.md b/CHANGELOG.md
index ae950b08b..f77baf81d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ User-visible changes worth mentioning.
 ## main
 
 - [#1696] Add missing `#issued_token` method to `OAuth::TokenResponse`
+- [#1697] Allow a TokenResponse body to be customized.
 
 ## 5.6.9
 
diff --git a/lib/doorkeeper/oauth/token_response.rb b/lib/doorkeeper/oauth/token_response.rb
index a000b0112..a1d44b493 100644
--- a/lib/doorkeeper/oauth/token_response.rb
+++ b/lib/doorkeeper/oauth/token_response.rb
@@ -12,7 +12,7 @@ def initialize(token)
       end
 
       def body
-        {
+        @body ||= {
           "access_token" => token.plaintext_token,
           "token_type" => token.token_type,
           "expires_in" => token.expires_in_seconds,
diff --git a/spec/lib/oauth/token_response_spec.rb b/spec/lib/oauth/token_response_spec.rb
index 8de8e6ea7..70a7de0a0 100644
--- a/spec/lib/oauth/token_response_spec.rb
+++ b/spec/lib/oauth/token_response_spec.rb
@@ -55,6 +55,28 @@
     end
   end
 
+  describe ".body attributes" do
+    subject(:token_response) { described_class.new(access_token) }
+
+    let(:access_token) do
+      double :access_token,
+             plaintext_token: "some-token",
+             expires_in: "3600",
+             expires_in_seconds: "300",
+             scopes_string: "two scopes",
+             plaintext_refresh_token: "some-refresh-token",
+             token_type: "Bearer",
+             custom_parameter: "custom_value",
+             created_at: 0
+    end
+
+    it "can be augmented" do
+      token_response.body["custom_parameter"] = access_token.custom_parameter
+
+      expect(token_response.body["custom_parameter"]).to eq("custom_value")
+    end
+  end
+
   describe ".body filters out empty values" do
     subject(:body) { described_class.new(access_token).body }