diff --git a/README.md b/README.md
index e75ed84..c184fbe 100644
--- a/README.md
+++ b/README.md
@@ -105,6 +105,7 @@ The following changes are already implemented:
 * 🤖 [User Badges](https://github.com/etkecc/synapse-admin/pull/160)
 * 🔑 [Allow prefilling any fields on the login form via GET params](https://github.com/etkecc/synapse-admin/pull/181)
 * 🖼️ [Add "Media" tab for rooms](https://github.com/etkecc/synapse-admin/pull/196)
+* ➕ [Support E.164-based Matrix IDs (MSC4009)](https://github.com/etkecc/synapse-admin/pull/214)
 
 #### exclusive for [etke.cc](https://etke.cc) customers
 
diff --git a/src/resources/users.tsx b/src/resources/users.tsx
index 9be6423..e33d200 100644
--- a/src/resources/users.tsx
+++ b/src/resources/users.tsx
@@ -191,7 +191,7 @@ export const UserList = (props: ListProps) => (
 // here only local part of user_id
 // maxLength = 255 - "@" - ":" - storage.getItem("home_server").length
 // storage.getItem("home_server").length is not valid here
-const validateUser = [required(), maxLength(253), regex(/^[a-z0-9._=\-/]+$/, "synapseadmin.users.invalid_user_id")];
+const validateUser = [required(), maxLength(253), regex(/^[a-z0-9._=\-\+/]+$/, "synapseadmin.users.invalid_user_id")];
 
 const validateAddress = [required(), maxLength(255)];
 
diff --git a/src/utils/mxid.ts b/src/utils/mxid.ts
index f5651b8..a46e266 100644
--- a/src/utils/mxid.ts
+++ b/src/utils/mxid.ts
@@ -41,7 +41,6 @@ export function returnMXID(input: string | Identifier): string {
   const homeserver = localStorage.getItem("home_server");
 
   // Check if the input already looks like a valid MXID (i.e., starts with "@" and contains ":")
-  const mxidPattern = /^@[^@:]+:[^@:]+$/;
   if (isMXID(input)) {
     return input as string; // Already a valid MXID
   }