diff --git a/src/source.ts b/src/source.ts
index 5823d172b..1b1c49ee9 100644
--- a/src/source.ts
+++ b/src/source.ts
@@ -1,4 +1,12 @@
-import { MarkupSource, MirSource, OutputType, Context, Kind, EventEmitter } from './types.js'
+import {
+  MarkupSource,
+  MirSource,
+  OutputType,
+  Context,
+  Kind,
+  EventEmitter,
+  KindOptions,
+} from './types.js'
 import { KIND_OPTIONS, CONTENT_TYPE_OPTIONS } from './constants.js'
 import { Cache } from './structures.js'
 import { Script } from './script.js'
@@ -7,10 +15,10 @@ import { OutgoingHttpHeaders } from 'http'
 
 export class Source {
   public kind: Kind
-  public kindOptions: { [key in Kind]: string }
+  public kindOptions: KindOptions
   public url: string
   public contentType: string
-  public contentTypeOptions: { [key in Kind]: string }
+  public contentTypeOptions: KindOptions
   public headers: OutgoingHttpHeaders
   public body?: object
   public script: Script
diff --git a/src/types.ts b/src/types.ts
index f85c1b728..24371ba2b 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -189,14 +189,16 @@ export type MarkupArgumentScript = {
   hierarchicalType: MarkupHierarchicalType.Argument
 }
 
+export type KindOptions = Record<Kind, string>
+
 export type MarkupSource = {
   kind: Kind
-  kindOptions: { [key in Kind]: string }
+  kindOptions: KindOptions
   headers: OutgoingHttpHeaders
   body?: object
   url: string
   contentType: string
-  contentTypeOptions: { [key in Kind]: string }
+  contentTypeOptions: KindOptions
   script: MarkupScript
   scriptId: number
 }
@@ -374,10 +376,10 @@ export type MirSource = {
   kind: Kind
   headers: OutgoingHttpHeaders
   body?: object
-  kindOptions: { [key in Kind]: string }
+  kindOptions: KindOptions
   url: string
   contentType: string
-  contentTypeOptions: { [key in Kind]: string }
+  contentTypeOptions: KindOptions
   script: MirScript
 }
 
diff --git a/test/src/radon.spec.ts b/test/src/radon.spec.ts
index 6e2810ed4..97a92d21b 100755
--- a/test/src/radon.spec.ts
+++ b/test/src/radon.spec.ts
@@ -3616,6 +3616,7 @@ describe('Radon', () => {
       expect(updatedSource.kind).toBe(2)
       expect(updatedSource.contentType).toBe('JSON API')
     })
+
     it('update to rng protocol kind', () => {
       const mirRequest: MirRequest = {
         timelock: 0,