diff --git a/patches/server/0252-Configurable-valid-characters-for-usernames.patch b/patches/server/0252-Configurable-valid-characters-for-usernames.patch
new file mode 100644
index 000000000..8f34e0ce2
--- /dev/null
+++ b/patches/server/0252-Configurable-valid-characters-for-usernames.patch
@@ -0,0 +1,35 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: BillyGalbreath <blake.galbreath@gmail.com>
+Date: Sat, 1 Jan 2022 18:38:58 -0600
+Subject: [PATCH] Configurable valid characters for usernames
+
+
+diff --git a/src/main/java/net/minecraft/server/network/ServerLoginPacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
+index c25df7de9adf6cc06d8d49d53c51d843f61565fa..757469c94ece79d1753db7f55d4d417ad8c0d489 100644
+--- a/src/main/java/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
++++ b/src/main/java/net/minecraft/server/network/ServerLoginPacketListenerImpl.java
+@@ -236,6 +236,8 @@ public class ServerLoginPacketListenerImpl implements ServerLoginPacketListener
+             return false;
+         }
+ 
++        if (true) return org.purpurmc.purpur.PurpurConfig.usernameValidCharactersPattern.matcher(in).matches(); // Purpur
++
+         for (int i = 0, len = in.length(); i < len; ++i) {
+             char c = in.charAt(i);
+ 
+diff --git a/src/main/java/org/purpurmc/purpur/PurpurConfig.java b/src/main/java/org/purpurmc/purpur/PurpurConfig.java
+index 9b07f3ff8ea84aa231e6b183bcd2947bb1b7e4bc..6eb138a83460e049f711c67055fe6db4ff812e8c 100644
+--- a/src/main/java/org/purpurmc/purpur/PurpurConfig.java
++++ b/src/main/java/org/purpurmc/purpur/PurpurConfig.java
+@@ -390,4 +390,11 @@ public class PurpurConfig {
+     private static void networkSettings() {
+         useUPnP = getBoolean("settings.network.upnp-port-forwarding", useUPnP);
+     }
++
++    public static java.util.regex.Pattern usernameValidCharactersPattern;
++    private static void usernameValidationSettings() {
++        String defaultPattern = "^[a-zA-Z0-9_.]*$";
++        String setPattern = getString("settings.username-valid-characters", defaultPattern);
++        usernameValidCharactersPattern = java.util.regex.Pattern.compile(setPattern == null || setPattern.isBlank() ? defaultPattern : setPattern);
++    }
+ }