diff --git a/bind/v4k.lua b/bind/v4k.lua
index 309983b..6595c6b 100644
--- a/bind/v4k.lua
+++ b/bind/v4k.lua
@@ -1420,6 +1420,7 @@ enum BILLBOARD_MODE {
  aabb model_aabb(model_t, mat44 transform);
  void model_lod(model_t*, float lo_detail, float hi_detail, float morph);
  void model_shading(model_t*, int shading);
+ void model_shading_custom(model_t*, int shading, const char *vs, const char *fs, const char *defines);
  void model_skybox(model_t*, skybox_t sky, bool load_sh);
  void model_render(model_t, mat44 proj, mat44 view, mat44 model, int shader);
  void model_render_skeleton(model_t, mat44 model);
diff --git a/engine/art/shaderlib/lightmap.glsl b/engine/art/shaderlib/lightmap.glsl
index c602c9d..3a3875a 100644
--- a/engine/art/shaderlib/lightmap.glsl
+++ b/engine/art/shaderlib/lightmap.glsl
@@ -1,5 +1,5 @@
+bool do_lightmap() {
 #ifdef LIGHTMAP_BAKING
-void main() {
     vec3 n = normalize(v_normal_ws);
     vec4 diffuse;
 
@@ -15,5 +15,8 @@ void main() {
     }
 
     fragcolor = vec4(diffuse.rgb*u_litboost, 1.0);
-}
-#endif
\ No newline at end of file
+    return true;
+#else
+    return false;
+#endif
+}
\ No newline at end of file
diff --git a/engine/art/shaders/fs_32_4_model.glsl b/engine/art/shaders/fs_32_4_model.glsl
index 5faffe9..7e79b6d 100644
--- a/engine/art/shaders/fs_32_4_model.glsl
+++ b/engine/art/shaders/fs_32_4_model.glsl
@@ -2,9 +2,9 @@
 #include "lightmap.glsl"
 #include "surface.glsl"
 
-#ifndef LIGHTMAP_BAKING
 void main() {
+    if (do_lightmap())
+        return;
     surface_t surf = surface();
     fragcolor = surf.fragcolor;
 }
-#endif