diff --git a/src/redux/actions/comments.js b/src/redux/actions/comments.js
index 0bcb8cb..a150a88 100644
--- a/src/redux/actions/comments.js
+++ b/src/redux/actions/comments.js
@@ -42,7 +42,7 @@ export function doCommentList(uri: string, page: number = 1, pageSize: number =
 export function doCommentCreate(
   comment: string = '',
   claim_id: string = '',
-  channel: ?string,
+  channel: string,
   parent_id?: string
 ) {
   return (dispatch: Dispatch, getState: GetState) => {