diff --git a/Jellyfin.Server.Implementations/Users/UserManager.cs b/Jellyfin.Server.Implementations/Users/UserManager.cs
index 41f1ac3519..269a3b7662 100644
--- a/Jellyfin.Server.Implementations/Users/UserManager.cs
+++ b/Jellyfin.Server.Implementations/Users/UserManager.cs
@@ -109,10 +109,10 @@ namespace Jellyfin.Server.Implementations.Users
             }
         }
 
-        // This is some regex that matches only on unicode "word" characters, as well as -, _ and @
+        // This is some regex that matches only on unicode "word" characters, as well as -, _, @, and +
         // In theory this will cut out most if not all 'control' characters which should help minimize any weirdness
-        // Usernames can contain letters (a-z + whatever else unicode is cool with), numbers (0-9), at-signs (@), dashes (-), underscores (_), apostrophes ('), periods (.) and spaces ( )
-        [GeneratedRegex(@"^[\w\ \-'._@]+$")]
+        // Usernames can contain letters (a-z + whatever else unicode is cool with), numbers (0-9), at-signs (@), dashes (-), underscores (_), apostrophes ('), periods (.), plus-signs (+), and spaces ( )
+        [GeneratedRegex("^[\\w\\ \\-\\+'._@]+$")]
         private static partial Regex ValidUsernameRegex();
 
         /// <inheritdoc/>
diff --git a/tests/Jellyfin.Server.Implementations.Tests/Users/UserManagerTests.cs b/tests/Jellyfin.Server.Implementations.Tests/Users/UserManagerTests.cs
index 867dda29d6..da6d492d2b 100644
--- a/tests/Jellyfin.Server.Implementations.Tests/Users/UserManagerTests.cs
+++ b/tests/Jellyfin.Server.Implementations.Tests/Users/UserManagerTests.cs
@@ -9,7 +9,12 @@ namespace Jellyfin.Server.Implementations.Tests.Users
         [Theory]
         [InlineData("this_is_valid")]
         [InlineData("this is also valid")]
+        [InlineData("this+too")]
         [InlineData("0@_-' .")]
+        [InlineData("john+doe")]
+        [InlineData("JöhnDøë")]
+        [InlineData("Jö hn+Døë")]
+        [InlineData("Jö hn+Døë@")]
         public void ThrowIfInvalidUsername_WhenValidUsername_DoesNotThrowArgumentException(string username)
         {
             var ex = Record.Exception(() => UserManager.ThrowIfInvalidUsername(username));