diff --git a/src/models/user.ts b/src/models/user.ts
index db10e06d8..0e9875504 100644
--- a/src/models/user.ts
+++ b/src/models/user.ts
@@ -147,8 +147,8 @@ export const isRemoteUser = (user: any): user is IRemoteUser =>
 	!isLocalUser(user);
 
 //#region Validators
-export function validateUsername(username: string): boolean {
-	return typeof username == 'string' && /^[a-zA-Z0-9_]{1,20}$/.test(username);
+export function validateUsername(username: string, remote?: boolean): boolean {
+	return typeof username == 'string' && (remote ? /^\w+([\w\.-]+\w+)?$/ : /^[a-zA-Z0-9_]{1,20}$/).test(username);
 }
 
 export function validatePassword(password: string): boolean {
diff --git a/src/remote/activitypub/models/person.ts b/src/remote/activitypub/models/person.ts
index 6f694a6ec..74fcdc10a 100644
--- a/src/remote/activitypub/models/person.ts
+++ b/src/remote/activitypub/models/person.ts
@@ -43,7 +43,7 @@ function validatePerson(x: any, uri: string) {
 		return new Error('invalid person: inbox is not a string');
 	}
 
-	if (!validateUsername(x.preferredUsername)) {
+	if (!validateUsername(x.preferredUsername, true)) {
 		return new Error('invalid person: invalid username');
 	}
 
diff --git a/src/server/api/endpoints/users/search.ts b/src/server/api/endpoints/users/search.ts
index b37c07003..85138fa6e 100644
--- a/src/server/api/endpoints/users/search.ts
+++ b/src/server/api/endpoints/users/search.ts
@@ -45,7 +45,7 @@ export const meta = {
 };
 
 export default define(meta, (ps, me) => new Promise(async (res, rej) => {
-	const isUsername = validateUsername(ps.query.replace('@', ''));
+	const isUsername = validateUsername(ps.query.replace('@', ''), true);
 
 	let users: IUser[] = [];