diff --git a/include/light/entities.hh b/include/light/entities.hh
index 27c5835e..b27995f6 100644
--- a/include/light/entities.hh
+++ b/include/light/entities.hh
@@ -72,6 +72,7 @@ public:
 public:
     lockable_vec_t light, atten, formula, spotangle, spotangle2, style, anglescale;
     lockable_vec_t dirtscale, dirtgain, dirt, deviance, samples, projfov;
+    lockable_vec_t dirt_off_radius, dirt_on_radius;
     lockable_bool_t bleed;
     lockable_vec3_t origin, color, mangle, projangle;
     lockable_string_t project_texture;
@@ -105,6 +106,8 @@ public:
         deviance { "deviance", 0 },
         samples { "samples", 16 },
         projfov { "project_fov", 90 },
+        dirt_off_radius { "dirt_off_radius", 0.0f },
+        dirt_on_radius { "dirt_on_radius", 0.0f },
         bleed { "bleed", false },
         origin { "origin", 0, 0, 0 },
         color { "color", 255.0f, 255.0f, 255.0f, vec3_transformer_t::NORMALIZE_COLOR_TO_255 },
@@ -123,6 +126,7 @@ public:
         return {{
             &light, &atten, &formula, &spotangle, &spotangle2, &style, &bleed, &anglescale,
             &dirtscale, &dirtgain, &dirt, &deviance, &samples, &projfov,
+            &dirt_off_radius, &dirt_on_radius,
             &origin, &color, &mangle, &projangle, &project_texture
         }};
     }
diff --git a/light/ltface.cc b/light/ltface.cc
index 29be10c3..38285709 100644
--- a/light/ltface.cc
+++ b/light/ltface.cc
@@ -1081,6 +1081,13 @@ Light_ClampMin(lightsample_t *sample, const vec_t light, const vec3_t color)
     }
 }
 
+static float fraction(float min, float val, float max) {
+    if (val >= max) return 1.0;
+    if (val <= min) return 0.0;
+    
+    return (val - min) / (max - min);
+}
+
 /*
  * ============
  * Dirt_GetScaleFactor
@@ -1089,7 +1096,7 @@ Light_ClampMin(lightsample_t *sample, const vec_t light, const vec3_t color)
  * ============
  */
 static inline vec_t
-Dirt_GetScaleFactor(const globalconfig_t &cfg, vec_t occlusion, const light_t *entity, const lightsurf_t *surf)
+Dirt_GetScaleFactor(const globalconfig_t &cfg, vec_t occlusion, const light_t *entity, const vec_t entitydist, const lightsurf_t *surf)
 {
     vec_t light_dirtgain = cfg.dirtGain.floatValue();
     vec_t light_dirtscale = cfg.dirtScale.floatValue();
@@ -1145,6 +1152,26 @@ Dirt_GetScaleFactor(const globalconfig_t &cfg, vec_t occlusion, const light_t *e
         outDirt = 1.0f;
     }
 
+    /* lerp based on distance to light */
+    if (entity) {
+        // From 0 to _dirt_off_radius units, no dirt.
+        // From _dirt_off_radius to _dirt_on_radius, the dirt linearly ramps from 0 to full, and after _dirt_on_radius, it's full dirt.
+        
+        if (entity->dirt_on_radius.isChanged()
+            && entity->dirt_off_radius.isChanged()) {
+            
+            const float onRadius = entity->dirt_on_radius.floatValue();
+            const float offRadius = entity->dirt_off_radius.floatValue();
+            
+            if (entitydist < offRadius) {
+                outDirt = 0.0;
+            } else if (entitydist >= offRadius && entitydist < onRadius) {
+                const float frac = fraction(offRadius, entitydist, onRadius);
+                outDirt = frac * outDirt;
+            }
+        }
+    }
+    
     /* return to sender */
     return 1.0f - outDirt;
 }
@@ -1293,7 +1320,7 @@ GetDirectLighting(const globalconfig_t &cfg, raystream_t *rs, const vec3_t origi
         
         GetLightContrib(cfg, &entity, normal, origin, false, color, surfpointToLightDir, normalcontrib, &surfpointToLightDist);
         
-        const float dirt = Dirt_GetScaleFactor(cfg, occlusion, &entity, /* FIXME: pass */ nullptr);
+        const float dirt = Dirt_GetScaleFactor(cfg, occlusion, &entity, surfpointToLightDist, /* FIXME: pass */ nullptr);
         VectorScale(color, dirt, color);
         
         // NOTE: Skip negative lights, which would make no sense to bounce!
@@ -1332,7 +1359,7 @@ GetDirectLighting(const globalconfig_t &cfg, raystream_t *rs, const vec3_t origi
         
         float dirt = 1;
         if (sun.dirt) {
-            dirt = Dirt_GetScaleFactor(cfg, occlusion, nullptr, /* FIXME: pass */ nullptr);
+            dirt = Dirt_GetScaleFactor(cfg, occlusion, nullptr, 0.0, /* FIXME: pass */ nullptr);
         }
         
         VectorMA(colorout, dirt * cosangle * sun.sunlight / 255.0f, sun.sunlight_color, colorout);
@@ -1392,7 +1419,7 @@ LightFace_Entity(const bsp2_t *bsp,
         
         GetLightContrib(cfg, entity, surfnorm, surfpoint, lightsurf->twosided, color, surfpointToLightDir, normalcontrib, &surfpointToLightDist);
  
-        const float occlusion = Dirt_GetScaleFactor(cfg, lightsurf->occlusion[i], entity, lightsurf);
+        const float occlusion = Dirt_GetScaleFactor(cfg, lightsurf->occlusion[i], entity, surfpointToLightDist, lightsurf);
         VectorScale(color, occlusion, color);
         
         /* Quick distance check first */
@@ -1481,7 +1508,7 @@ LightFace_Sky(const sun_t *sun, const lightsurf_t *lightsurf, lightmapdict_t *li
         angle = (1.0 - sun->anglescale) + sun->anglescale * angle;
         float value = angle * sun->sunlight;
         if (sun->dirt) {
-            value *= Dirt_GetScaleFactor(cfg, lightsurf->occlusion[i], NULL, lightsurf);
+            value *= Dirt_GetScaleFactor(cfg, lightsurf->occlusion[i], NULL, 0.0, lightsurf);
         }
         
         vec3_t color, normalcontrib;
@@ -1548,7 +1575,7 @@ LightFace_Min(const bsp2_t *bsp, const bsp2_dface_t *face,
         
         vec_t value = light;
         if (cfg.minlightDirt.boolValue()) {
-            value *= Dirt_GetScaleFactor(cfg, lightsurf->occlusion[i], NULL, lightsurf);
+            value *= Dirt_GetScaleFactor(cfg, lightsurf->occlusion[i], NULL, 0.0, lightsurf);
         }
         if (cfg.addminlight.boolValue()) {
             Light_Add(sample, value, color, vec3_origin);
@@ -1608,7 +1635,7 @@ LightFace_Min(const bsp2_t *bsp, const bsp2_dface_t *face,
             vec_t value = entity.light.floatValue();
             lightsample_t *sample = &lightmap->samples[i];
             
-            value *= Dirt_GetScaleFactor(cfg, lightsurf->occlusion[i], &entity, lightsurf);
+            value *= Dirt_GetScaleFactor(cfg, lightsurf->occlusion[i], &entity, 0.0 /* TODO: pass distance */, lightsurf);
             if (cfg.addminlight.boolValue()) {
                 Light_Add(sample, value, *entity.color.vec3Value(), vec3_origin);
             } else {
@@ -1640,7 +1667,7 @@ LightFace_DirtDebug(const lightsurf_t *lightsurf, lightmapdict_t *lightmaps)
     /* Overwrite each point with the dirt value for that sample... */
     for (int i = 0; i < lightsurf->numpoints; i++) {
         lightsample_t *sample = &lightmap->samples[i];
-        const float light = 255 * Dirt_GetScaleFactor(cfg, lightsurf->occlusion[i], NULL, lightsurf);
+        const float light = 255 * Dirt_GetScaleFactor(cfg, lightsurf->occlusion[i], NULL, 0.0, lightsurf);
         VectorSet(sample->color, light, light, light);
     }
 
@@ -1832,7 +1859,7 @@ LightFace_Bounce(const bsp2_t *bsp, const bsp2_dface_t *face, const lightsurf_t
              * Except, not in bouncedebug mode.
              */
             if (debugmode != debugmode_bounce) {
-                const vec_t dirtscale = Dirt_GetScaleFactor(cfg, lightsurf->occlusion[i], NULL, lightsurf);
+                const vec_t dirtscale = Dirt_GetScaleFactor(cfg, lightsurf->occlusion[i], NULL, 0.0, lightsurf);
                 VectorScale(indirect, dirtscale, indirect);
             }
             
diff --git a/testmaps/dirttest2.map b/testmaps/dirttest2.map
index 3a4d94e7..26a1fd5b 100644
--- a/testmaps/dirttest2.map
+++ b/testmaps/dirttest2.map
@@ -4,16 +4,53 @@
 {
 "classname" "worldspawn"
 "wad" "free_wad.wad"
+"_dirt" "1"
 // brush 0
 {
 ( -1056 -864 576 ) ( -1056 -880 576 ) ( -1056 -864 896 ) stuff4 0 0 0 1 1
 ( -1248 -1152 576 ) ( -1256 -1144 576 ) ( -1248 -1152 736 ) stuff4 0 0 0 1 1
 ( -1312 -936 576 ) ( -1312 -920 576 ) ( -1312 -936 832 ) stuff4 0 0 0 1 1
-( -1024 -896 456 ) ( -1024 -896 480 ) ( -1056 -896 480 ) stuff4 0 0 0 1 1
+( -1024 -592 456 ) ( -1024 -592 480 ) ( -1056 -592 480 ) stuff4 -0 -0 -0 1 1
 ( -1136 -1152 576 ) ( -1152 -1152 576 ) ( -1136 -1152 832 ) stuff4 0 0 0 1 1
 ( -1096 -1152 736 ) ( -1080 -1152 736 ) ( -1096 -1184 736 ) stuff4 0 0 0 -1 1
 ( -1120 -1184 576 ) ( -1120 -1200 576 ) ( -1056 -1184 576 ) stuff4 0 0 0 1 1
 }
+// brush 1
+{
+( -1280 -896 896 ) ( -1088 -896 912 ) ( -1088 -896 896 ) stuff4 32 0 0 1 1
+( -1280 -896 896 ) ( -1280 -640 912 ) ( -1280 -896 912 ) stuff4 32 0 0 1 1
+( -1280 -896 896 ) ( -1088 -640 896 ) ( -1280 -640 896 ) stuff4 32 0 0 1 1
+( -1280 -896 912 ) ( -1088 -640 912 ) ( -1088 -896 912 ) stuff4 32 0 0 1 1
+( -1280 -592 896 ) ( -1088 -592 912 ) ( -1280 -592 912 ) stuff4 32 -0 -0 1 1
+( -1056 -896 896 ) ( -1056 -640 912 ) ( -1056 -640 896 ) stuff4 32 -0 -0 1 1
+}
+// brush 2
+{
+( -1232 -1136 928 ) ( -1056 -1136 944 ) ( -1056 -1136 928 ) stuff4 0 0 0 1 1
+( -1232 -1136 928 ) ( -1232 -896 944 ) ( -1232 -1136 944 ) stuff4 0 0 0 1 1
+( -1232 -1136 928 ) ( -1056 -896 928 ) ( -1232 -896 928 ) stuff4 0 0 0 1 1
+( -1232 -1136 944 ) ( -1056 -896 944 ) ( -1056 -1136 944 ) stuff4 0 0 0 1 1
+( -1232 -912 928 ) ( -1056 -912 944 ) ( -1232 -912 944 ) stuff4 -0 -0 -0 1 1
+( -1056 -1136 928 ) ( -1056 -896 944 ) ( -1056 -896 928 ) stuff4 0 0 0 1 1
+}
+// brush 3
+{
+( -1056 -1152 720 ) ( -1024 -1152 736 ) ( -1024 -1152 720 ) stuff4 -0 16 -0 1 1
+( -1056 -1152 720 ) ( -1056 -864 736 ) ( -1056 -1152 736 ) stuff4 -0 16 -0 1 1
+( -1056 -1152 720 ) ( -1024 -864 720 ) ( -1056 -864 720 ) stuff4 -0 -0 -0 1 1
+( -1056 -1152 928 ) ( -1024 -864 928 ) ( -1024 -1152 928 ) stuff4 -0 -0 -0 1 1
+( -1056 -592 720 ) ( -1024 -592 736 ) ( -1056 -592 736 ) stuff4 -0 16 -0 1 1
+( -1024 -1152 720 ) ( -1024 -864 736 ) ( -1024 -864 720 ) stuff4 -0 16 -0 1 1
+}
+// brush 4
+{
+( -1248 -592 720 ) ( -1056 -592 736 ) ( -1056 -592 720 ) stuff4 0 0 0 1 1
+( -1248 -592 720 ) ( -1248 -560 736 ) ( -1248 -592 736 ) stuff4 0 0 0 1 1
+( -1248 -592 720 ) ( -1056 -560 720 ) ( -1248 -560 720 ) stuff4 0 0 0 1 1
+( -1248 -592 896 ) ( -1056 -560 896 ) ( -1056 -592 896 ) stuff4 -0 -0 -0 1 1
+( -1248 -576 720 ) ( -1056 -576 736 ) ( -1248 -576 736 ) stuff4 -0 -0 -0 1 1
+( -1056 -592 720 ) ( -1056 -560 736 ) ( -1056 -560 720 ) stuff4 0 0 0 1 1
+}
 }
 // entity 1
 {
@@ -117,7 +154,7 @@
 }
 // brush 5
 {
-( -1088 -1240 760 ) ( -1088 -1240 768 ) ( -1088 -808 768 ) stuff4 32 0 90 1 1
+( -1056 -1240 760 ) ( -1056 -1240 768 ) ( -1056 -808 768 ) stuff4 32 -0 90 1 1
 ( -1272 -912 928 ) ( -1272 -912 896 ) ( -1280 -896 896 ) stuff4 32 0 90 1 1
 ( -1072 -896 896 ) ( -1104 -896 896 ) ( -1104 -896 888 ) stuff4 32 0 90 1 1
 ( -1272 -912 896 ) ( -1272 -912 928 ) ( -1088 -912 928 ) stuff4 0 -16 0 1 1
@@ -135,7 +172,7 @@
 }
 // brush 7
 {
-( -1088 -1240 768 ) ( -1088 -808 768 ) ( -1088 -808 760 ) stuff4 32 0 90 1 1
+( -1056 -1240 768 ) ( -1056 -808 768 ) ( -1056 -808 760 ) stuff4 32 -0 90 1 1
 ( -1248 -1152 896 ) ( -1240 -1136 896 ) ( -1240 -1136 928 ) stuff4 32 0 90 1 1
 ( -1088 -1136 928 ) ( -1272 -1136 928 ) ( -1272 -1136 896 ) stuff4 0 -16 0 1 1
 ( -1104 -1152 888 ) ( -1104 -1152 896 ) ( -1072 -1152 896 ) stuff4 32 0 90 1 1
@@ -157,7 +194,7 @@
 "classname" "func_group"
 // brush 0
 {
-( -1216 -912 512 ) ( -1216 -928 512 ) ( -1216 -912 768 ) stuff4 32 0 0 1 1
+( -1056 -912 512 ) ( -1056 -928 512 ) ( -1056 -912 768 ) stuff4 32 -0 -0 1 1
 ( -1248 -1152 512 ) ( -1248 -1152 832 ) ( -1248 -1184 832 ) stuff4 32 0 0 1 1
 ( -1248 -1152 832 ) ( -1248 -1152 512 ) ( -1024 -1152 512 ) stuff4 0 0 0 -1 1
 ( -1192 -1184 512 ) ( -1208 -1184 512 ) ( -1192 -1184 768 ) stuff4 32 0 0 1 1
@@ -177,7 +214,7 @@
 {
 ( -1248 -864 640 ) ( -1248 -880 640 ) ( -1248 -864 960 ) stuff4 32 0 0 1 1
 ( -1280 -896 896 ) ( -1280 -896 736 ) ( -1280 -864 736 ) stuff4 32 0 0 1 1
-( -1056 -864 520 ) ( -1056 -864 544 ) ( -1088 -864 544 ) stuff4 32 0 0 1 1
+( -1056 -592 520 ) ( -1056 -592 544 ) ( -1088 -592 544 ) stuff4 32 -0 -0 1 1
 ( -1280 -896 736 ) ( -1280 -896 896 ) ( -1248 -896 896 ) stuff4 32 0 0 1 1
 ( -1128 -1120 896 ) ( -1112 -1120 896 ) ( -1128 -1152 896 ) stuff4 32 0 0 1 1
 ( -1160 -1152 736 ) ( -1160 -1168 736 ) ( -1096 -1152 736 ) stuff4 32 0 0 1 1
@@ -229,7 +266,7 @@
 }
 // brush 8
 {
-( -1088 -912 576 ) ( -1088 -928 576 ) ( -1088 -912 832 ) stuff4 32 0 0 1 1
+( -1056 -912 576 ) ( -1056 -928 576 ) ( -1056 -912 832 ) stuff4 32 -0 -0 1 1
 ( -1248 -1152 576 ) ( -1248 -1152 896 ) ( -1248 -1184 896 ) stuff4 32 0 0 1 1
 ( -1248 -1152 896 ) ( -1248 -1152 576 ) ( -1024 -1152 576 ) stuff4 0 0 0 -1 1
 ( -1192 -1184 576 ) ( -1208 -1184 576 ) ( -1192 -1184 832 ) stuff4 32 0 0 1 1
@@ -252,3 +289,12 @@
 "origin" "-1152 -1024 760"
 "angle" "180"
 }
+// entity 6
+{
+"classname" "light"
+"origin" "-1272 -1096 856"
+"angle" "-0"
+"wait" "0.3"
+"_dirt_off_radius" "100"
+"_dirt_on_radius" "500"
+}