diff --git a/include/light/light.hh b/include/light/light.hh
index b8015fff..edf7c0ad 100644
--- a/include/light/light.hh
+++ b/include/light/light.hh
@@ -157,7 +157,8 @@ typedef enum {
     debugmode_dirt,
     debugmode_bounce,
     debugmode_bouncelights,
-    debugmode_contribfaces
+    debugmode_contribfaces,
+    debugmode_debugoccluded
 } debugmode_t;
 
 extern debugmode_t debugmode;
diff --git a/light/light.cc b/light/light.cc
index 91c44a6a..81881f7f 100644
--- a/light/light.cc
+++ b/light/light.cc
@@ -995,6 +995,9 @@ light_main(int argc, const char **argv)
             
             ParseVec3(dump_face_point, &i, argc, argv);
             dump_face = true;
+        } else if ( !strcmp( argv[ i ], "-debugoccluded" ) ) {
+            CheckNoDebugModeSet();
+            debugmode = debugmode_debugoccluded;
         } else if ( !strcmp( argv[ i ], "-verbose" ) ) {
             verbose_log = true;
         } else if ( !strcmp( argv[ i ], "-help" ) ) {
diff --git a/light/ltface.cc b/light/ltface.cc
index 5ad3dd36..1a7939dd 100644
--- a/light/ltface.cc
+++ b/light/ltface.cc
@@ -1729,6 +1729,26 @@ LightFace_ContribFacesDebug(const lightsurf_t *lightsurf, lightmapdict_t *lightm
     Lightmap_Save(lightmaps, lightsurf, lightmap, 0);
 }
 
+static void
+LightFace_OccludedDebug(const lightsurf_t *lightsurf, lightmapdict_t *lightmaps)
+{
+    Q_assert(debugmode == debugmode_debugoccluded);
+    
+    /* use a style 0 light map */
+    lightmap_t *lightmap = Lightmap_ForStyle(lightmaps, 0, lightsurf);
+    
+    /* Overwrite each point, red=occluded, green=ok */
+    for (int i = 0; i < lightsurf->numpoints; i++) {
+        lightsample_t *sample = &lightmap->samples[i];
+        if (lightsurf->occluded[i])
+            glm_to_vec3_t(glm::vec3(255,0,0), sample->color);
+        else
+            glm_to_vec3_t(glm::vec3(0,255,0), sample->color);
+    }
+    
+    Lightmap_Save(lightmaps, lightsurf, lightmap, 0);
+}
+
 
 /* Dirtmapping borrowed from q3map2, originally by RaP7oR */
 
@@ -2518,6 +2538,9 @@ LightFace(const bsp2_t *bsp, bsp2_dface_t *face, facesup_t *facesup, const globa
     if (debugmode == debugmode_contribfaces)
         LightFace_ContribFacesDebug(lightsurf, lightmaps);
     
+    if (debugmode == debugmode_debugoccluded)
+        LightFace_OccludedDebug(lightsurf, lightmaps);
+    
     /* Apply gamma, rangescale, and clamp */
     LightFace_ScaleAndClamp(lightsurf, lightmaps);