diff --git a/src/maploader/maploader.cpp b/src/maploader/maploader.cpp
index 4268880b17..7ebd5dd387 100644
--- a/src/maploader/maploader.cpp
+++ b/src/maploader/maploader.cpp
@@ -2984,7 +2984,11 @@ void MapLoader::InitLevelMesh(MapData* map)
 
 	if (Level->lightmaps)
 	{
-		LoadLightmap(map);
+		if (!LoadLightmap(map))
+		{
+			Level->levelMesh->PackLightmapAtlas();
+		}
+
 		Level->levelMesh->BindLightmapSurfacesToGeometry(*Level);
 	}
 	else
@@ -2993,30 +2997,30 @@ void MapLoader::InitLevelMesh(MapData* map)
 	}
 }
 
-void MapLoader::LoadLightmap(MapData* map)
+bool MapLoader::LoadLightmap(MapData* map)
 {
 	if (!map->Size(ML_LIGHTMAP))
-		return;
+		return false;
 
 	FileReader fr;
 	if (!fr.OpenDecompressor(map->Reader(ML_LIGHTMAP), -1, FileSys::METHOD_ZLIB, false, true))
-		return;
+		return false;
 
 	int version = fr.ReadInt32();
 	if (version == 0)
 	{
 		Printf(PRINT_HIGH, "LoadLightmap: This is an old unsupported alpha version of the lightmap lump. Please rebuild the map with a newer version of zdray.\n");
-		return;
+		return false;
 	}
 	if (version == 1)
 	{
 		Printf(PRINT_HIGH, "LoadLightmap: This is an old unsupported version of the lightmap lump. Please rebuild the map with a newer version of zdray.\n");
-		return;
+		return false;
 	}
 	if (version != 2)
 	{
 		Printf(PRINT_HIGH, "LoadLightmap: unsupported lightmap lump version\n");
-		return;
+		return false;
 	}
 
 	uint32_t numSurfaces = fr.ReadUInt32();
@@ -3029,7 +3033,7 @@ void MapLoader::LoadLightmap(MapData* map)
 	}
 
 	if (numSurfaces == 0 || numTexCoords == 0 || numTexPixels == 0)
-		return;
+		return false;
 
 	bool errors = false;
 
@@ -3073,7 +3077,8 @@ void MapLoader::LoadLightmap(MapData* map)
 	};
 
 	TMap<DoomLevelMeshSurface*, int> detectedSurfaces;
-	TArray<SurfaceEntry> zdraySurfaces; // TODO reserve ahead of time 'numSurfaces'
+	TArray<SurfaceEntry> zdraySurfaces;
+	zdraySurfaces.Reserve(numSurfaces);
 
 	for (auto& surface : Level->levelMesh->Surfaces)
 	{
@@ -3092,6 +3097,7 @@ void MapLoader::LoadLightmap(MapData* map)
 		}
 	}
 
+	uint32_t usedSurfaceIndex = 0;
 	for (uint32_t i = 0; i < numSurfaces; i++)
 	{
 		SurfaceEntry surface;
@@ -3160,12 +3166,19 @@ void MapLoader::LoadLightmap(MapData* map)
 		}
 		else
 		{
+			levelSurface->texWidth = surface.width;
+			levelSurface->texHeight = surface.height;
+
 			surface.targetSurface = levelSurface;
 			detectedSurfaces.Insert(levelSurface, 1);
-			zdraySurfaces.Push(surface);
+			zdraySurfaces[usedSurfaceIndex++] = surface;
 		}
 	}
 
+	Level->levelMesh->PackLightmapAtlas();
+
+	zdraySurfaces.Resize(usedSurfaceIndex);
+
 	if (developer >= 1)
 	{
 		Printf("Lightmap contains %d surfaces out of which %d were successfully matched.\n", numSurfaces, zdraySurfaces.Size());
@@ -3310,7 +3323,7 @@ void MapLoader::LoadLightmap(MapData* map)
 	// Use UVs from the lightmap
 	for (auto& surface : zdraySurfaces)
 	{
-		auto& realSurface = Level->levelMesh->Surfaces[findSurfaceIndex(surface.type, surface.typeIndex, getControlSector(surface.controlSector))];
+		auto& realSurface = *surface.targetSurface;
 
 		auto* UVs = &Level->levelMesh->LightmapUvs[realSurface.startUvIndex];
 		auto* newUVs = &zdrayUvs[surface.uvOffset];
diff --git a/src/maploader/maploader.h b/src/maploader/maploader.h
index 3dcbddc182..90cccf87a2 100644
--- a/src/maploader/maploader.h
+++ b/src/maploader/maploader.h
@@ -305,7 +305,7 @@ public:
 	void CopySlopes();
 
 	void InitLevelMesh(MapData* map);
-	void LoadLightmap(MapData* map);
+	bool LoadLightmap(MapData* map);
 
 	void LoadLevel(MapData *map, const char *lumpname, int position);
 
diff --git a/src/rendering/hwrenderer/doom_levelmesh.cpp b/src/rendering/hwrenderer/doom_levelmesh.cpp
index 800bbbe4ae..74a8204ad8 100644
--- a/src/rendering/hwrenderer/doom_levelmesh.cpp
+++ b/src/rendering/hwrenderer/doom_levelmesh.cpp
@@ -1070,17 +1070,24 @@ void DoomLevelMesh::SetupLightmapUvs()
 {
 	LMTextureSize = 1024; // TODO cvar
 
+	for (auto& surface : Surfaces)
+	{
+		BuildSurfaceParams(LMTextureSize, LMTextureSize, surface);
+	}
+
+	BuildSmoothingGroups();
+}
+
+void DoomLevelMesh::PackLightmapAtlas()
+{
 	std::vector<LevelMeshSurface*> sortedSurfaces;
 	sortedSurfaces.reserve(Surfaces.Size());
 
 	for (auto& surface : Surfaces)
 	{
-		BuildSurfaceParams(LMTextureSize, LMTextureSize, surface);
 		sortedSurfaces.push_back(&surface);
 	}
 
-	BuildSmoothingGroups();
-
 	std::sort(sortedSurfaces.begin(), sortedSurfaces.end(), [](LevelMeshSurface* a, LevelMeshSurface* b) { return a->texHeight != b->texHeight ? a->texHeight > b->texHeight : a->texWidth > b->texWidth; });
 
 	RectPacker packer(LMTextureSize, LMTextureSize, RectPacker::Spacing(0));
diff --git a/src/rendering/hwrenderer/doom_levelmesh.h b/src/rendering/hwrenderer/doom_levelmesh.h
index aa9c4d8831..43360ff78a 100644
--- a/src/rendering/hwrenderer/doom_levelmesh.h
+++ b/src/rendering/hwrenderer/doom_levelmesh.h
@@ -30,6 +30,7 @@ public:
 	void CreatePortals();
 	void DumpMesh(const FString& objFilename, const FString& mtlFilename) const;
 	void BindLightmapSurfacesToGeometry(FLevelLocals& doomMap);
+	void PackLightmapAtlas();
 
 	bool TraceSky(const FVector3& start, FVector3 direction, float dist)
 	{
diff --git a/src/rendering/hwrenderer/scene/hw_drawinfo.h b/src/rendering/hwrenderer/scene/hw_drawinfo.h
index 34b2b968e5..f67c9bb8da 100644
--- a/src/rendering/hwrenderer/scene/hw_drawinfo.h
+++ b/src/rendering/hwrenderer/scene/hw_drawinfo.h
@@ -214,7 +214,7 @@ struct HWDrawInfo
 		{
 			surface->needsUpdate = true;
 		}
-		else if (VisibleSurfaces.Size() >= lm_max_updates)
+		else if (VisibleSurfaces.Size() >= unsigned(lm_max_updates))
 		{
 			return;
 		}