diff --git a/polygerrit-ui/app/utils/account-util.ts b/polygerrit-ui/app/utils/account-util.ts
index a7d0587..207152c 100644
--- a/polygerrit-ui/app/utils/account-util.ts
+++ b/polygerrit-ui/app/utils/account-util.ts
@@ -29,7 +29,7 @@
 const SUGGESTIONS_LIMIT = 15;
 // https://html.spec.whatwg.org/multipage/input.html#valid-e-mail-address
 export const MENTIONS_REGEX =
-  /(?<=^|\s)@([a-zA-Z0-9.!#$%&'*+=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*)(?=\s+|$)/g;
+  /(?:^|\s)@([a-zA-Z0-9.!#$%&'*+=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*)(?=\s+|$)/g;
 
 export function accountKey(account: AccountInfo): AccountId | EmailAddress {
   if (account._account_id !== undefined) return account._account_id;