diff --git a/Source/Core/Core/Core.cpp b/Source/Core/Core/Core.cpp
index e08c3f58d2..604de6f170 100644
--- a/Source/Core/Core/Core.cpp
+++ b/Source/Core/Core/Core.cpp
@@ -29,6 +29,7 @@
 #include "Core/Host.h"
 #include "Core/MemTools.h"
 #include "Core/Movie.h"
+#include "Core/NetPlayClient.h"
 #include "Core/NetPlayProto.h"
 #include "Core/PatchEngine.h"
 #include "Core/State.h"
@@ -129,6 +130,12 @@ void SetIsFramelimiterTempDisabled(bool disable)
 std::string GetStateFileName() { return s_state_filename; }
 void SetStateFileName(const std::string& val) { s_state_filename = val; }
 
+void FrameUpdateOnCPUThread()
+{
+	if (NetPlay::IsNetPlayRunning())
+		NetPlayClient::SendTimeBase();
+}
+
 // Display messages and return values
 
 // Formatted stop message
diff --git a/Source/Core/Core/Core.h b/Source/Core/Core/Core.h
index b86168f3f6..1eea2be226 100644
--- a/Source/Core/Core/Core.h
+++ b/Source/Core/Core/Core.h
@@ -63,6 +63,8 @@ void SetStateFileName(const std::string& val);
 
 void SetBlockStart(u32 addr);
 
+void FrameUpdateOnCPUThread();
+
 bool ShouldSkipFrame(int skipped);
 void VideoThrottle();
 void RequestRefreshInfo();
diff --git a/Source/Core/Core/Movie.cpp b/Source/Core/Core/Movie.cpp
index b59ff1d78a..de457e7b16 100644
--- a/Source/Core/Core/Movie.cpp
+++ b/Source/Core/Core/Movie.cpp
@@ -17,6 +17,7 @@
 #include "Core/Core.h"
 #include "Core/CoreTiming.h"
 #include "Core/Movie.h"
+#include "Core/NetPlayClient.h"
 #include "Core/NetPlayProto.h"
 #include "Core/State.h"
 #include "Core/DSP/DSPCore.h"
@@ -139,6 +140,8 @@ std::string GetInputDisplay()
 
 void FrameUpdate()
 {
+	// TODO[comex]: This runs on the GPU thread, yet it messes with the CPU
+	// state directly.  That's super sketchy.
 	g_currentFrame++;
 	if (!s_bPolled)
 		g_currentLagCount++;
diff --git a/Source/Core/Core/NetPlayClient.cpp b/Source/Core/Core/NetPlayClient.cpp
index 3f53d58a32..eeae193110 100644
--- a/Source/Core/Core/NetPlayClient.cpp
+++ b/Source/Core/Core/NetPlayClient.cpp
@@ -442,6 +442,26 @@ unsigned int NetPlayClient::OnData(sf::Packet& packet)
 	}
 	break;
 
+	case NP_MSG_DESYNC_DETECTED:
+	{
+		int pid_to_blame;
+		u32 frame;
+		packet >> pid_to_blame;
+		packet >> frame;
+		const char* blame_str = "";
+		const char* blame_name = "";
+		std::lock_guard<std::recursive_mutex> lkp(m_crit.players);
+		if (pid_to_blame != -1)
+		{
+			auto it = m_players.find(pid_to_blame);
+			blame_str = " from player ";
+			blame_name = it != m_players.end() ? it->second.name.c_str() : "??";
+		}
+
+		m_dialog->AppendChat(StringFromFormat("/!\\ Possible desync detected%s%s on frame %u", blame_str, blame_name, frame));
+	}
+	break;
+
 	default:
 		PanicAlertT("Unknown message received with id : %d", mid);
 		break;
@@ -643,6 +663,8 @@ bool NetPlayClient::StartGame(const std::string &path)
 
 	m_dialog->AppendChat(" -- STARTING GAME -- ");
 
+	m_timebase_frame = 0;
+
 	m_is_running.store(true);
 	NetPlay_Enable(this);
 
@@ -1044,6 +1066,20 @@ u8 NetPlayClient::LocalWiimoteToInGameWiimote(u8 local_pad)
 	return ingame_pad;
 }
 
+void NetPlayClient::SendTimeBase()
+{
+	std::lock_guard<std::mutex> lk(crit_netplay_client);
+
+	u64 timebase = SystemTimers::GetFakeTimeBase();
+
+	sf::Packet* spac = new sf::Packet;
+	*spac << (MessageId)NP_MSG_TIMEBASE;
+	*spac << (u32)timebase;
+	*spac << (u32)(timebase << 32);
+	*spac << netplay_client->m_timebase_frame++;
+	netplay_client->SendAsync(spac);
+}
+
 // stuff hacked into dolphin
 
 // called from ---CPU--- thread
diff --git a/Source/Core/Core/NetPlayClient.h b/Source/Core/Core/NetPlayClient.h
index ce5d0ee63b..c80afda9f7 100644
--- a/Source/Core/Core/NetPlayClient.h
+++ b/Source/Core/Core/NetPlayClient.h
@@ -77,6 +77,8 @@ public:
 
 	u8 LocalWiimoteToInGameWiimote(u8 local_pad);
 
+	static void SendTimeBase();
+
 	enum State
 	{
 		WaitingForTraversalClientConnection,
@@ -141,6 +143,8 @@ private:
 	std::string m_player_name;
 	bool m_connecting;
 	TraversalClient* m_traversal_client;
+
+	u32 m_timebase_frame;
 };
 
 void NetPlay_Enable(NetPlayClient* const np);
diff --git a/Source/Core/Core/NetPlayProto.h b/Source/Core/Core/NetPlayProto.h
index 7f17e0aa60..e473c660fa 100644
--- a/Source/Core/Core/NetPlayProto.h
+++ b/Source/Core/Core/NetPlayProto.h
@@ -29,7 +29,7 @@ struct Rpt : public std::vector<u8>
 
 typedef std::vector<u8> NetWiimote;
 
-#define NETPLAY_VERSION  "Dolphin NetPlay 2014-01-08"
+#define NETPLAY_VERSION  "Dolphin NetPlay 2015-03-10"
 
 extern u64 g_netplay_initial_gctime;
 
@@ -53,6 +53,9 @@ enum
 	NP_MSG_STOP_GAME = 0xA2,
 	NP_MSG_DISABLE_GAME = 0xA3,
 
+	NP_MSG_TIMEBASE = 0xB0,
+	NP_MSG_DESYNC_DETECTED = 0xB1,
+
 	NP_MSG_READY = 0xD0,
 	NP_MSG_NOT_READY = 0xD1,
 
diff --git a/Source/Core/Core/NetPlayServer.cpp b/Source/Core/Core/NetPlayServer.cpp
index f53793f3be..aa10e56afb 100644
--- a/Source/Core/Core/NetPlayServer.cpp
+++ b/Source/Core/Core/NetPlayServer.cpp
@@ -110,7 +110,6 @@ void NetPlayServer::ThreadFunc()
 	while (m_do_loop)
 	{
 		// update pings every so many seconds
-
 		if ((m_ping_timer.GetTimeElapsed() > 1000) || m_update_pings)
 		{
 			m_ping_key = Common::Timer::GetTimeMs();
@@ -581,6 +580,53 @@ unsigned int NetPlayServer::OnData(sf::Packet& packet, Client& player)
 	}
 	break;
 
+	case NP_MSG_TIMEBASE:
+	{
+		u32 x, y, frame;
+		packet >> x;
+		packet >> y;
+		packet >> frame;
+
+		if (m_desync_detected)
+			break;
+
+		u64 timebase = x | ((u64)y << 32);
+		std::vector<std::pair<PlayerId, u64>>& timebases = m_timebase_by_frame[frame];
+		timebases.emplace_back(player.pid, timebase);
+		if (timebases.size() >= m_players.size())
+		{
+			// we have all records for this frame
+
+			if (!std::all_of(timebases.begin(), timebases.end(), [&](std::pair<PlayerId, u64> pair){ return pair.second == timebases[0].second; }))
+			{
+				int pid_to_blame = -1;
+				if (timebases.size() > 2)
+				{
+					for (auto pair : timebases)
+					{
+						if (std::all_of(timebases.begin(), timebases.end(), [&](std::pair<PlayerId, u64> other) {
+							return other.first == pair.first || other.second != pair.second;
+						}))
+						{
+							// we are the only outlier
+							pid_to_blame = pair.first;
+							break;
+						}
+					}
+				}
+
+				sf::Packet spac;
+				spac << (MessageId) NP_MSG_DESYNC_DETECTED;
+				spac << pid_to_blame;
+				spac << frame;
+				SendToClients(spac);
+
+				m_desync_detected = true;
+			}
+			m_timebase_by_frame.erase(frame);
+		}
+	}
+	break;
 	default:
 		PanicAlertT("Unknown message with id:%d received from player:%d Kicking player!", mid, player.pid);
 		// unknown message, kick the client
@@ -635,6 +681,8 @@ void NetPlayServer::SetNetSettings(const NetSettings &settings)
 // called from ---GUI--- thread
 bool NetPlayServer::StartGame()
 {
+	m_timebase_by_frame.clear();
+	m_desync_detected = false;
 	std::lock_guard<std::recursive_mutex> lkg(m_crit.game);
 	m_current_game = Common::Timer::GetTimeMs();
 
diff --git a/Source/Core/Core/NetPlayServer.h b/Source/Core/Core/NetPlayServer.h
index 73f8d6d85e..842c795c38 100644
--- a/Source/Core/Core/NetPlayServer.h
+++ b/Source/Core/Core/NetPlayServer.h
@@ -9,6 +9,7 @@
 #include <queue>
 #include <sstream>
 #include <thread>
+#include <unordered_map>
 #include <unordered_set>
 #include <SFML/Network/Packet.hpp>
 #include "Common/Timer.h"
@@ -99,6 +100,9 @@ private:
 
 	std::map<PlayerId, Client> m_players;
 
+	std::unordered_map<u32, std::vector<std::pair<PlayerId, u64>>> m_timebase_by_frame;
+	bool m_desync_detected;
+
 	struct
 	{
 		std::recursive_mutex game;
diff --git a/Source/Core/VideoCommon/PixelEngine.cpp b/Source/Core/VideoCommon/PixelEngine.cpp
index 45db963d23..91662e9931 100644
--- a/Source/Core/VideoCommon/PixelEngine.cpp
+++ b/Source/Core/VideoCommon/PixelEngine.cpp
@@ -11,6 +11,7 @@
 #include "Common/ChunkFile.h"
 #include "Common/CommonTypes.h"
 #include "Core/ConfigManager.h"
+#include "Core/Core.h"
 #include "Core/CoreTiming.h"
 #include "Core/State.h"
 #include "Core/HW/MMIO.h"
@@ -282,6 +283,8 @@ void SetFinish_OnMainThread(u64 userdata, int cyclesLate)
 	s_signal_finish_interrupt.store(1);
 	UpdateInterrupts();
 	CommandProcessor::SetInterruptFinishWaiting(false);
+
+	Core::FrameUpdateOnCPUThread();
 }
 
 // SetToken