diff --git a/src/Server.ts b/src/Server.ts
index 55ca533..2c68132 100644
--- a/src/Server.ts
+++ b/src/Server.ts
@@ -151,7 +151,7 @@ export class Server {
         if (maybeMatrixUser) {
             return maybeMatrixUser;
         }
-        const localPart = mxid.split(":")[0].substring(1)
+        const localPart = mxid.split(":")[0].substring(1).replace(' ', '-20');
         if (!this.nickToMatrixUser.has(localPart)) {
             const newMatrixUser = new MatrixUser(mxid, localPart);
             this.matrixUsers.set(mxid, newMatrixUser);