diff --git a/WireGuard/WireGuard/Model/Configuration.swift b/WireGuard/WireGuard/Model/Configuration.swift
index 3cc59af..8ef93e6 100644
--- a/WireGuard/WireGuard/Model/Configuration.swift
+++ b/WireGuard/WireGuard/Model/Configuration.swift
@@ -18,7 +18,7 @@ struct InterfaceConfiguration: Codable {
     var privateKey: Data
     var addresses: [IPAddressRange] = []
     var listenPort: UInt16? = nil
-    var mtu: UInt64? = nil
+    var mtu: UInt16? = nil
     var dns: [DNSServer] = []
 
     var publicKey: Data {
diff --git a/WireGuard/WireGuard/UI/TunnelViewModel.swift b/WireGuard/WireGuard/UI/TunnelViewModel.swift
index cb678d1..bc826d5 100644
--- a/WireGuard/WireGuard/UI/TunnelViewModel.swift
+++ b/WireGuard/WireGuard/UI/TunnelViewModel.swift
@@ -134,11 +134,11 @@ class TunnelViewModel {
                 }
             }
             if let mtuString = scratchpad[.mtu] {
-                if let mtu = UInt64(mtuString) {
+                if let mtu = UInt16(mtuString) {
                     config.mtu = mtu
                 } else {
                     fieldsWithError.insert(.mtu)
-                    errorMessages.append("Interface's MTU should be a number")
+                    errorMessages.append("Interface's MTU should be a 16-bit integer (0 to 65535)")
                 }
             }
             if let dnsString = scratchpad[.dns] {