diff --git a/server/lemmy_utils/src/lib.rs b/server/lemmy_utils/src/lib.rs
index fc50e199b..1a89beaa7 100644
--- a/server/lemmy_utils/src/lib.rs
+++ b/server/lemmy_utils/src/lib.rs
@@ -162,6 +162,11 @@ pub fn is_valid_username(name: &str) -> bool {
   VALID_USERNAME_REGEX.is_match(name)
 }
 
+// Can't do a regex here, reverse lookarounds not supported
+pub fn is_valid_preferred_username(preferred_username: &str) -> bool {
+  !preferred_username.starts_with("@") && preferred_username.len() >=3 && preferred_username.len() <= 20
+}
+
 pub fn is_valid_community_name(name: &str) -> bool {
   VALID_COMMUNITY_NAME_REGEX.is_match(name)
 }
@@ -176,6 +181,7 @@ mod tests {
     is_valid_community_name,
     is_valid_post_title,
     is_valid_username,
+    is_valid_preferred_username,
     remove_slurs,
     scrape_text_for_mentions,
     slur_check,
@@ -201,6 +207,12 @@ mod tests {
     assert!(!is_valid_username(""));
   }
 
+  #[test]
+  fn test_valid_preferred_username() {
+    assert!(is_valid_preferred_username("hello @there"));
+    assert!(!is_valid_preferred_username("@hello there"));
+  }
+
   #[test]
   fn test_valid_community_name() {
     assert!(is_valid_community_name("example"));
diff --git a/server/src/api/user.rs b/server/src/api/user.rs
index 2d5895170..83d8470cd 100644
--- a/server/src/api/user.rs
+++ b/server/src/api/user.rs
@@ -51,6 +51,7 @@ use lemmy_db::{
 use lemmy_utils::{
   generate_actor_keypair,
   generate_random_string,
+  is_valid_preferred_username,
   is_valid_username,
   make_apub_endpoint,
   naive_from_unix,
@@ -576,7 +577,12 @@ impl Perform for Oper<SaveUserSettings> {
 
     // The DB constraint should stop too many characters
     let preferred_username = match &data.preferred_username {
-      Some(preferred_username) => Some(preferred_username.to_owned()),
+      Some(preferred_username) => {
+        if !is_valid_preferred_username(preferred_username.trim()) {
+          return Err(APIError::err("invalid_username").into());
+        }
+        Some(preferred_username.trim().to_string())
+      }
       None => read_user.preferred_username,
     };
 
diff --git a/ui/src/components/user-details.tsx b/ui/src/components/user-details.tsx
index 5e9a58d22..b3ce294f3 100644
--- a/ui/src/components/user-details.tsx
+++ b/ui/src/components/user-details.tsx
@@ -79,6 +79,7 @@ export class UserDetails extends Component<UserDetailsProps, UserDetailsState> {
 
   componentDidMount() {
     this.fetchUserData();
+    setupTippy();
   }
 
   componentDidUpdate(lastProps: UserDetailsProps) {
@@ -88,7 +89,6 @@ export class UserDetails extends Component<UserDetailsProps, UserDetailsState> {
         break;
       }
     }
-    setupTippy();
   }
 
   fetchUserData() {
diff --git a/ui/src/components/user.tsx b/ui/src/components/user.tsx
index d7db0ae2a..13cc90aca 100644
--- a/ui/src/components/user.tsx
+++ b/ui/src/components/user.tsx
@@ -180,6 +180,7 @@ export class User extends Component<any, UserState> {
       );
 
     WebSocketService.Instance.getSite();
+    setupTippy();
   }
 
   get isCurrentUser() {
@@ -226,7 +227,6 @@ export class User extends Component<any, UserState> {
       // Couldnt get a refresh working. This does for now.
       location.reload();
     }
-    setupTippy();
   }
 
   get documentTitle(): string {
@@ -565,6 +565,7 @@ export class User extends Component<any, UserState> {
                       this,
                       this.handleUserSettingsPreferredUsernameChange
                     )}
+                    pattern="^(?!@)(.+)$"
                     minLength={3}
                     maxLength={20}
                   />