diff --git a/src/maploader/maploader.cpp b/src/maploader/maploader.cpp
index b6305b88b..bf7f3be57 100644
--- a/src/maploader/maploader.cpp
+++ b/src/maploader/maploader.cpp
@@ -3033,12 +3033,12 @@ bool MapLoader::LoadLightmap(MapData* map)
 		return false;
 
 	int version = fr.ReadInt32();
-	if (version < 3)
+	if (version < LIGHTMAPVER)
 	{
-		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");
+		Printf(PRINT_HIGH, "LoadLightmap: This is an old unsupported version of the lightmap lump. Please rebuild the map with the console commands 'deletelightmap', and then 'savelightmap'.\n");
 		return false;
 	}
-	else if (version != 3)
+	else if (version != LIGHTMAPVER)
 	{
 		Printf(PRINT_HIGH, "LoadLightmap: unsupported lightmap lump version\n");
 		return false;
diff --git a/src/rendering/hwrenderer/doom_levelmesh.cpp b/src/rendering/hwrenderer/doom_levelmesh.cpp
index aab151dbb..300d4bf53 100644
--- a/src/rendering/hwrenderer/doom_levelmesh.cpp
+++ b/src/rendering/hwrenderer/doom_levelmesh.cpp
@@ -2002,11 +2002,13 @@ void SaveMapLumps(FileWriter* writer, const TArray<MapLump>& lumps, const char*
 void DoomLevelMesh::SaveLightmapLump(FLevelLocals& doomMap)
 {
 	/*
-	// LIGHTMAP V3 pseudo-C specification:
+	// LIGHTMAP version 4 pseudo-C specification:
+
+	(Please update LIGHTMAPVER in version.h when upgrading this)
 
 	struct LightmapLump
 	{
-		int version = 2;
+		int version;
 		uint32_t tileCount;
 		uint32_t pixelCount;
 		uint32_t uvCount;
@@ -2046,7 +2048,7 @@ void DoomLevelMesh::SaveLightmapLump(FLevelLocals& doomMap)
 		}
 	}
 
-	const int version = 3;
+	const int version = LIGHTMAPVER;
 
 	const uint32_t headerSize = sizeof(int) + 2 * sizeof(uint32_t);
 	const uint32_t bytesPerTileEntry = sizeof(uint32_t) * 4 + sizeof(uint16_t) * 2 + sizeof(float) * 9;
diff --git a/src/version.h b/src/version.h
index f63ca3fea..4feeb2db1 100644
--- a/src/version.h
+++ b/src/version.h
@@ -127,5 +127,7 @@ const int SAVEPICHEIGHT = 162;
 const int VID_MIN_WIDTH = 320;
 const int VID_MIN_HEIGHT = 200;
 
+// Lightmap lump version
+#define LIGHTMAPVER 4
 
 #endif //__VERSION_H__