diff --git a/Source/Core/Core/NetPlayClient.cpp b/Source/Core/Core/NetPlayClient.cpp
index 212a938c6c..bcab00351f 100644
--- a/Source/Core/Core/NetPlayClient.cpp
+++ b/Source/Core/Core/NetPlayClient.cpp
@@ -244,25 +244,25 @@ bool NetPlayClient::Connect()
     return false;
   }
 
-  MessageId error;
+  ConnectionError error;
   rpac >> error;
 
   // got error message
-  if (error)
+  if (error != ConnectionError::NoError)
   {
     switch (error)
     {
-    case CON_ERR_SERVER_FULL:
+    case ConnectionError::ServerFull:
       m_dialog->OnConnectionError(_trans("The server is full."));
       break;
-    case CON_ERR_VERSION_MISMATCH:
+    case ConnectionError::VersionMismatch:
       m_dialog->OnConnectionError(
           _trans("The server and client's NetPlay versions are incompatible."));
       break;
-    case CON_ERR_GAME_RUNNING:
+    case ConnectionError::GameRunning:
       m_dialog->OnConnectionError(_trans("The game is currently running."));
       break;
-    case CON_ERR_NAME_TOO_LONG:
+    case ConnectionError::NameTooLong:
       m_dialog->OnConnectionError(_trans("Nickname is too long."));
       break;
     default:
diff --git a/Source/Core/Core/NetPlayProto.h b/Source/Core/Core/NetPlayProto.h
index f24c1efbe5..4a2e4d263c 100644
--- a/Source/Core/Core/NetPlayProto.h
+++ b/Source/Core/Core/NetPlayProto.h
@@ -179,12 +179,13 @@ enum class MessageID : u8
   SyncCodes = 0xF2,
 };
 
-enum
+enum class ConnectionError : u8
 {
-  CON_ERR_SERVER_FULL = 1,
-  CON_ERR_GAME_RUNNING = 2,
-  CON_ERR_VERSION_MISMATCH = 3,
-  CON_ERR_NAME_TOO_LONG = 4
+  NoError = 0,
+  ServerFull = 1,
+  GameRunning = 2,
+  VersionMismatch = 3,
+  NameTooLong = 4
 };
 
 enum class SyncSaveDataID : u8
diff --git a/Source/Core/Core/NetPlayServer.cpp b/Source/Core/Core/NetPlayServer.cpp
index b26d1f5c91..f75daf2208 100644
--- a/Source/Core/Core/NetPlayServer.cpp
+++ b/Source/Core/Core/NetPlayServer.cpp
@@ -297,16 +297,16 @@ void NetPlayServer::ThreadFunc()
         if (!netEvent.peer->data)
         {
           // uninitialized client, we'll assume this is their initialization packet
-          unsigned int error;
+          ConnectionError error;
           {
             std::lock_guard lkg(m_crit.game);
             error = OnConnect(netEvent.peer, rpac);
           }
 
-          if (error)
+          if (error != ConnectionError::NoError)
           {
             sf::Packet spac;
-            spac << static_cast<MessageId>(error);
+            spac << error;
             // don't need to lock, this client isn't in the client map
             Send(netEvent.peer, spac);
 
@@ -374,7 +374,7 @@ static void SendSyncIdentifier(sf::Packet& spac, const SyncIdentifier& sync_iden
 }
 
 // called from ---NETPLAY--- thread
-unsigned int NetPlayServer::OnConnect(ENetPeer* socket, sf::Packet& rpac)
+ConnectionError NetPlayServer::OnConnect(ENetPeer* socket, sf::Packet& rpac)
 {
   // give new client first available id
   PlayerId pid = 1;
@@ -392,15 +392,15 @@ unsigned int NetPlayServer::OnConnect(ENetPeer* socket, sf::Packet& rpac)
   rpac >> npver;
   // Dolphin netplay version
   if (npver != Common::scm_rev_git_str)
-    return CON_ERR_VERSION_MISMATCH;
+    return ConnectionError::VersionMismatch;
 
   // game is currently running or game start is pending
   if (m_is_running || m_start_pending)
-    return CON_ERR_GAME_RUNNING;
+    return ConnectionError::GameRunning;
 
   // too many players
   if (m_players.size() >= 255)
-    return CON_ERR_SERVER_FULL;
+    return ConnectionError::ServerFull;
 
   Client player;
   player.pid = pid;
@@ -410,7 +410,7 @@ unsigned int NetPlayServer::OnConnect(ENetPeer* socket, sf::Packet& rpac)
   rpac >> player.name;
 
   if (StringUTF8CodePointCount(player.name) > MAX_NAME_LENGTH)
-    return CON_ERR_NAME_TOO_LONG;
+    return ConnectionError::NameTooLong;
 
   // cause pings to be updated
   m_update_pings = true;
@@ -488,7 +488,7 @@ unsigned int NetPlayServer::OnConnect(ENetPeer* socket, sf::Packet& rpac)
     UpdateWiimoteMapping();
   }
 
-  return 0;
+  return ConnectionError::NoError;
 }
 
 // called from ---NETPLAY--- thread
diff --git a/Source/Core/Core/NetPlayServer.h b/Source/Core/Core/NetPlayServer.h
index 87c1d46f63..76c1d7ae94 100644
--- a/Source/Core/Core/NetPlayServer.h
+++ b/Source/Core/Core/NetPlayServer.h
@@ -129,7 +129,7 @@ private:
   void SendToClients(const sf::Packet& packet, PlayerId skip_pid = 0,
                      u8 channel_id = DEFAULT_CHANNEL);
   void Send(ENetPeer* socket, const sf::Packet& packet, u8 channel_id = DEFAULT_CHANNEL);
-  unsigned int OnConnect(ENetPeer* socket, sf::Packet& rpac);
+  ConnectionError OnConnect(ENetPeer* socket, sf::Packet& rpac);
   unsigned int OnDisconnect(const Client& player);
   unsigned int OnData(sf::Packet& packet, Client& player);