diff --git a/plugins/rendermax/renderer_light.cpp b/plugins/rendermax/renderer_light.cpp
index 65d54e3e7..dd138e04d 100644
--- a/plugins/rendermax/renderer_light.cpp
+++ b/plugins/rendermax/renderer_light.cpp
@@ -271,15 +271,15 @@ void lightingEngineViewscreen::doOcupancyAndLights()
                         {
                             if(bld->mat_type == 3)//green glass
                             {
-                                curCell=lightCell(0.1f,0.9f,0.5f);
+                                curCell*=lightCell(0.1f,0.9f,0.5f);
                             }
                             else if(bld->mat_type == 4)//clear glass
                             {
-                                curCell=lightCell(0.5f,0.95f,0.9f);
+                                curCell*=lightCell(0.5f,0.95f,0.9f);
                             }
                             else if(bld->mat_type == 5)//crystal glass
                             {
-                                curCell=lightCell(0.75f,0.95f,0.95f);
+                                curCell*=lightCell(0.75f,0.95f,0.95f);
                             }
                         }
                     }
diff --git a/plugins/rendermax/renderer_opengl.hpp b/plugins/rendermax/renderer_opengl.hpp
index b7529284f..14de2441a 100644
--- a/plugins/rendermax/renderer_opengl.hpp
+++ b/plugins/rendermax/renderer_opengl.hpp
@@ -199,6 +199,17 @@ struct lightCell
     {
         return lightCell(r*val,g*val,b*val);
     }
+    lightCell operator*(lightCell cell)
+    {
+        return lightCell(r*cell.r,g*cell.g,b*cell.b);
+    }
+    lightCell operator*=(lightCell cell)
+    {
+        r*=cell.r;
+        g*=cell.g;
+        b*=cell.b;
+        return lightCell(r,g,b);
+    }
     lightCell operator+(const lightCell& other)
     {
         return lightCell(r+other.r,g+other.g,b+other.b);