diff --git a/src/commandlets/commandlet.cpp b/src/commandlets/commandlet.cpp
index cfd236edf..ff167fac5 100644
--- a/src/commandlets/commandlet.cpp
+++ b/src/commandlets/commandlet.cpp
@@ -2,9 +2,12 @@
 #include "commandlet.h"
 #include "lightmapcmd.h"
 #include "version.h"
+#include "v_draw.h"
+#include "v_video.h"
 #include <functional>
 
 int D_DoomMain_Game();
+void D_BeginDoomLoop();
 static std::function<void()>* ToolCallback;
 extern bool DisableLogging;
 
@@ -17,8 +20,11 @@ int ToolMain()
 
 void Commandlet::RunInGame(std::function<void()> action)
 {
-	std::function<void()> callback = [=]() {
+	std::function<void()> callback = [&]() {
 		DisableLogging = false;
+
+		D_BeginDoomLoop();
+		twod->Begin(screen->GetWidth(), screen->GetHeight());
 		action();
 	};
 
diff --git a/src/commandlets/lightmapcmd.cpp b/src/commandlets/lightmapcmd.cpp
index 318f5b82c..4cc9d4483 100644
--- a/src/commandlets/lightmapcmd.cpp
+++ b/src/commandlets/lightmapcmd.cpp
@@ -1,5 +1,10 @@
 
 #include "lightmapcmd.h"
+#include "g_levellocals.h"
+#include "d_event.h"
+
+void G_SetMap(const char* mapname, int mode);
+void D_SingleTick();
 
 LightmapCmdletGroup::LightmapCmdletGroup()
 {
@@ -20,8 +25,24 @@ LightmapBuildCmdlet::LightmapBuildCmdlet()
 
 void LightmapBuildCmdlet::OnCommand(FArgs args)
 {
-	RunInGame([]() {
+	RunInGame([&]() {
+
+		FString mapname;
+		if (args.NumArgs() > 0 && args.GetArg(0)[0] != '-')
+			mapname = args.GetArg(0);
+		else
+			mapname = "map01";
+
+		G_SetMap(mapname.GetChars(), 0);
+		for (int i = 0; i < 100; i++)
+		{
+			D_SingleTick();
+			if (gameaction == ga_nothing)
+				break;
+		}
+
 		Printf("Baking LIGHTMAP lump!\n");
+		Printf("Current map is %s", level.LevelName.GetChars());
 	});
 }
 
diff --git a/src/d_main.cpp b/src/d_main.cpp
index 38522ad31..e6484ff2b 100644
--- a/src/d_main.cpp
+++ b/src/d_main.cpp
@@ -1216,6 +1216,33 @@ void D_ErrorCleanup ()
 	ClearGlobalVMStack();
 }
 
+void D_BeginDoomLoop()
+{
+	// Clamp the timer to TICRATE until the playloop has been entered.
+	r_NoInterpolate = true;
+	Page.SetInvalid();
+	Subtitle = nullptr;
+	Advisory.SetInvalid();
+}
+
+void D_SingleTick()
+{
+	I_StartTic();
+	D_ProcessEvents();
+	G_BuildTiccmd(&netcmds[consoleplayer][maketic % BACKUPTICS]);
+	if (advancedemo)
+		D_DoAdvanceDemo();
+	C_Ticker();
+	M_Ticker();
+	G_Ticker();
+	// [RH] Use the consoleplayer's camera to update sounds
+	S_UpdateSounds(players[consoleplayer].camera);	// move positional sounds
+	gametic++;
+	maketic++;
+	GC::CheckGC();
+	Net_NewMakeTic();
+}
+
 //==========================================================================
 //
 // D_DoomLoop
@@ -1227,16 +1254,11 @@ void D_ErrorCleanup ()
 
 void D_DoomLoop ()
 {
-	int lasttic = 0;
-
-	// Clamp the timer to TICRATE until the playloop has been entered.
-	r_NoInterpolate = true;
-	Page.SetInvalid();
-	Subtitle = nullptr;
-	Advisory.SetInvalid();
-
+	D_BeginDoomLoop();
 	vid_cursor->Callback();
 
+	int lasttic = 0;
+
 	for (;;)
 	{
 		try
@@ -1254,20 +1276,7 @@ void D_DoomLoop ()
 			// process one or more tics
 			if (singletics)
 			{
-				I_StartTic ();
-				D_ProcessEvents ();
-				G_BuildTiccmd (&netcmds[consoleplayer][maketic%BACKUPTICS]);
-				if (advancedemo)
-					D_DoAdvanceDemo ();
-				C_Ticker ();
-				M_Ticker ();
-				G_Ticker ();
-				// [RH] Use the consoleplayer's camera to update sounds
-				S_UpdateSounds (players[consoleplayer].camera);	// move positional sounds
-				gametic++;
-				maketic++;
-				GC::CheckGC ();
-				Net_NewMakeTic ();
+				D_SingleTick();
 			}
 			else
 			{
diff --git a/src/g_level.cpp b/src/g_level.cpp
index fbd500008..b8ed812dc 100644
--- a/src/g_level.cpp
+++ b/src/g_level.cpp
@@ -305,6 +305,30 @@ void G_DeferedInitNew (FNewGameStartup *gs)
 //
 //==========================================================================
 
+void G_SetMap(const char* mapname, int mode)
+{
+	if (!strcmp(mapname, "*")) mapname = primaryLevel->MapName.GetChars();
+
+	if (!P_CheckMapData(mapname))
+	{
+		Printf("No map %s\n", mapname);
+	}
+	else
+	{
+		if (mode == 1)
+		{
+			deathmatch = false;
+			multiplayernext = true;
+		}
+		else if (mode == 2)
+		{
+			deathmatch = true;
+			multiplayernext = true;
+		}
+		G_DeferedInitNew(mapname);
+	}
+}
+
 CCMD (map)
 {
 	if (netgame)
@@ -316,28 +340,15 @@ CCMD (map)
 	if (argv.argc() > 1)
 	{
 		const char *mapname = argv[1];
-		if (!strcmp(mapname, "*")) mapname = primaryLevel->MapName.GetChars();
 
 		try
 		{
-			if (!P_CheckMapData(mapname))
-			{
-				Printf ("No map %s\n", mapname);
-			}
-			else
-			{
-				if (argv.argc() > 2 && stricmp(argv[2], "coop") == 0)
-				{
-					deathmatch = false;
-					multiplayernext = true;
-				}
-				else if (argv.argc() > 2 && stricmp(argv[2], "dm") == 0)
-				{
-					deathmatch = true;
-					multiplayernext = true;
-				}
-				G_DeferedInitNew (mapname);
-			}
+			int mode = 0;
+			if (argv.argc() > 2 && stricmp(argv[2], "coop") == 0)
+				mode = 1;
+			else if (argv.argc() > 2 && stricmp(argv[2], "dm") == 0)
+				mode = 2;
+			G_SetMap(mapname, mode);
 		}
 		catch(CRecoverableError &error)
 		{