diff --git a/src/user.js b/src/user.js
index f7fcca79..a8149712 100644
--- a/src/user.js
+++ b/src/user.js
@@ -381,6 +381,19 @@ User.prototype.guestLogin = function (name) {
         return;
     }
 
+    if (name.match(Config.get("reserved-names.usernames"))) {
+        LOGGER.warn(
+            'Rejecting attempt by %s to use reserved username "%s"',
+            self.realip,
+            name
+        );
+        self.socket.emit("login", {
+            success: false,
+            error: "That username is reserved."
+        });
+        return;
+    }
+
     // Prevent duplicate logins
     self.setFlag(Flags.U_LOGGING_IN);
     db.users.isUsernameTaken(name, function (err, taken) {
diff --git a/src/web/auth.js b/src/web/auth.js
index 90f9bbea..0fa4795c 100644
--- a/src/web/auth.js
+++ b/src/web/auth.js
@@ -190,6 +190,11 @@ function handleRegister(req, res) {
     }
 
     if (name.match(Config.get("reserved-names.usernames"))) {
+        LOGGER.warn(
+            'Rejecting attempt by %s to register reserved username "%s"',
+            ip,
+            name
+        );
         sendPug(res, "register", {
             registerError: "That username is reserved"
         });