diff --git a/client/coral-framework/graphql/mutations/index.js b/client/coral-framework/graphql/mutations/index.js
index ef5359eb1..a9d08da85 100644
--- a/client/coral-framework/graphql/mutations/index.js
+++ b/client/coral-framework/graphql/mutations/index.js
@@ -25,7 +25,7 @@ export const postComment = graphql(POST_COMMENT, {
                 id: ownProps.auth.user.id,
                 name: ownProps.auth.user.username
               },
-              created_at: new Date().toString(),
+              created_at: new Date().toISOString(),
               body,
               parent_id,
               asset_id,