diff --git a/src/types/events/base-events.spec.ts b/src/types/events/base-events.spec.ts
new file mode 100644
index 000000000..f852e8438
--- /dev/null
+++ b/src/types/events/base-events.spec.ts
@@ -0,0 +1,41 @@
+import { assert } from 'chai';
+import { AppMentionEvent } from './base-events';
+
+describe('Events API payload types', () => {
+  it('should be compatible with app_mention payload', () => {
+    const payload: AppMentionEvent = {
+      type: 'app_mention',
+      text: '<@U066C7XNE6M> hey',
+      files: [{ id: 'F111' }],
+      upload: false,
+      user: 'U03E94MK0',
+      display_as_bot: false,
+      ts: '1707806347.397809',
+      blocks: [
+        {
+          type: 'rich_text',
+          block_id: 't9D3L',
+          elements: [
+            {
+              type: 'rich_text_section',
+              elements: [
+                {
+                  type: 'user',
+                  user_id: 'U066C7XNE6M',
+                },
+                {
+                  type: 'text',
+                  text: ' hey',
+                },
+              ],
+            },
+          ],
+        },
+      ],
+      client_msg_id: '883e5317-28e3-4ef8-9385-b88343560de6',
+      channel: 'CHE2DUW5V',
+      event_ts: '1707806347.397809',
+    };
+    assert.isNotEmpty(payload);
+  });
+});
diff --git a/src/types/events/base-events.ts b/src/types/events/base-events.ts
index 8c5bdb9be..b5ad2a2bd 100644
--- a/src/types/events/base-events.ts
+++ b/src/types/events/base-events.ts
@@ -189,12 +189,16 @@ export interface AppMentionEvent {
   subtype?: string;
   bot_id?: string;
   bot_profile?: BotProfile;
-  username: string;
+  username?: string;
   team?: string;
   user?: string;
   text: string;
   attachments?: MessageAttachment[];
   blocks?: (KnownBlock | Block)[];
+  // TODO: Add more properties once the types library has a file object definition
+  files?: { id: string }[];
+  upload?: boolean;
+  display_as_bot?: boolean;
   edited?: {
     user: string;
     ts: string;
@@ -203,6 +207,7 @@ export interface AppMentionEvent {
   channel: string;
   event_ts: string;
   thread_ts?: string;
+  client_msg_id?: string;
 }
 
 export interface AppRateLimitedEvent {