diff --git a/src/engine/renderer/GeometryOptimiser.cpp b/src/engine/renderer/GeometryOptimiser.cpp
index 43cbc82b0f..9c84cf252b 100644
--- a/src/engine/renderer/GeometryOptimiser.cpp
+++ b/src/engine/renderer/GeometryOptimiser.cpp
@@ -645,12 +645,12 @@ std::vector<MaterialSurface> OptimiseMapGeometryMaterial( world_t* world, bspSur
 			uint32_t texData = lhs.texDataDynamic[stage]
 				? ( lhs.texDataIDs[stage] + materialSystem.GetTexDataSize() ) << TEX_BUNDLE_BITS
 					: lhs.texDataIDs[stage] << TEX_BUNDLE_BITS;
-				texData |= ( HasLightMap( &lhs ) ? GetLightMapNum( &lhs ) : 255 ) << LIGHTMAP_BITS;
+				texData |= MaterialSystem::GetLightMapIdx( lhs, tr.worldLight ) << LIGHTMAP_BITS;
 
 			uint32_t texData2 = rhs.texDataDynamic[stage]
 				? ( rhs.texDataIDs[stage] + materialSystem.GetTexDataSize() ) << TEX_BUNDLE_BITS
 					: rhs.texDataIDs[stage] << TEX_BUNDLE_BITS;
-				texData2 |= ( HasLightMap( &rhs ) ? GetLightMapNum( &rhs ) : 255 ) << LIGHTMAP_BITS;
+				texData2 |= MaterialSystem::GetLightMapIdx( rhs, tr.worldLight ) << LIGHTMAP_BITS;
 
 			if ( texData < texData2 ) {
 				return true;
diff --git a/src/engine/renderer/Material.cpp b/src/engine/renderer/Material.cpp
index cb4c0cfcb3..0af6db50f0 100644
--- a/src/engine/renderer/Material.cpp
+++ b/src/engine/renderer/Material.cpp
@@ -480,6 +480,18 @@ void MaterialSystem::GenerateTexturesBuffer( std::vector<TextureData>& textures,
 	}
 }
 
+int MaterialSystem::GetLightMapIdx( const MaterialSurface &surface, lightMode_t mode )
+{
+	if ( mode == lightMode_t::MAP )
+	{
+		return GetLightMapNum( &surface ) & 255;
+	}
+	else
+	{
+		return 255;
+	}
+}
+
 // This generates the buffers with indirect rendering commands etc.
 void MaterialSystem::GenerateWorldCommandBuffer( std::vector<MaterialSurface>& surfaces ) {
 	Log::Debug( "Generating world command buffer" );
@@ -680,7 +692,7 @@ void MaterialSystem::GenerateWorldCommandBuffer( std::vector<MaterialSurface>& s
 			surfaceCommand.drawCommand.baseInstance |= surface.texDataDynamic[stage]
 				? ( surface.texDataIDs[stage] + texData.size() ) << TEX_BUNDLE_BITS
 				: surface.texDataIDs[stage] << TEX_BUNDLE_BITS;
-			surfaceCommand.drawCommand.baseInstance |= ( HasLightMap( &surface ) ? GetLightMapNum( &surface ) : 255 ) << LIGHTMAP_BITS;
+			surfaceCommand.drawCommand.baseInstance |= GetLightMapIdx( surface, tr.worldLight ) << LIGHTMAP_BITS;
 			surfaceCommands[cmdID] = surfaceCommand;
 
 			material->drawCommandCount++;
diff --git a/src/engine/renderer/Material.h b/src/engine/renderer/Material.h
index 5a25b70179..22a6f02d4e 100644
--- a/src/engine/renderer/Material.h
+++ b/src/engine/renderer/Material.h
@@ -356,6 +356,8 @@ class MaterialSystem {
 
 	bool frameStart = false;
 
+	static int GetLightMapIdx( const MaterialSurface &surface, lightMode_t mode );
+
 	void AddPortalSurfaces();
 	void AddAutospriteSurfaces();
 	void RenderMaterials( const shaderSort_t fromSort, const shaderSort_t toSort, const uint32_t viewID );