diff --git a/index.js b/index.ts
similarity index 82%
rename from index.js
rename to index.ts
index c047969..a948bab 100644
--- a/index.js
+++ b/index.ts
@@ -17,12 +17,14 @@
  * under the License.
  */
 
-// TODO Migrate this to a .ts file for v7.6.1 https://github.com/elastic/kibana/pull/55194
-
 import { resolve } from 'path';
 import { existsSync } from 'fs';
 
-const milestonesPluginInitializer = ({ Plugin }) =>
+import { Legacy } from 'kibana';
+
+import { LegacyPluginApi, LegacyPluginInitializer } from '../../src/legacy/types';
+
+const milestonesPluginInitializer: LegacyPluginInitializer = ({ Plugin }: LegacyPluginApi) =>
   new Plugin({
     id: 'kibana_milestones_vis',
     require: ['kibana', 'elasticsearch', 'data'],
@@ -34,13 +36,13 @@ const milestonesPluginInitializer = ({ Plugin }) =>
       ].find(p => existsSync(p)),
       hacks: [resolve(__dirname, 'public/legacy')],
     },
-    init: () => ({}),
-    config(Joi) {
+    init: (server: Legacy.Server) => ({}),
+    config(Joi: any) {
       return Joi.object({
         enabled: Joi.boolean().default(true),
       }).default();
     },
-  });
+  } as Legacy.PluginSpecOptions);
 
 // eslint-disable-next-line import/no-default-export
 export default milestonesPluginInitializer;