diff --git a/src/types/utilities.spec.ts b/src/types/utilities.spec.ts
index 5e49550c8..7c334b093 100644
--- a/src/types/utilities.spec.ts
+++ b/src/types/utilities.spec.ts
@@ -12,4 +12,15 @@ describe('RespondArguments', () => {
     };
     assert.exists(args);
   });
+  it('has metadata', () => {
+    const args: RespondArguments = {
+      response_type: 'in_channel',
+      text: 'Hey!',
+      metadata: {
+        event_type: 'test-event',
+        event_payload: { foo: 'bar' },
+      },
+    };
+    assert.exists(args);
+  });
 });
diff --git a/src/types/utilities.ts b/src/types/utilities.ts
index bbace32bb..03d85a628 100644
--- a/src/types/utilities.ts
+++ b/src/types/utilities.ts
@@ -9,6 +9,7 @@ type ChatPostMessageArgumentsKnownKeys =
   | 'as_user'
   | 'attachments'
   | 'blocks'
+  | 'metadata'
   | 'icon_emoji'
   | 'icon_url'
   | 'link_names'