diff --git a/include/light/entities.h b/include/light/entities.h
index dfaa808c..59837c98 100644
--- a/include/light/entities.h
+++ b/include/light/entities.h
@@ -71,6 +71,7 @@ typedef struct entity_s {
     /* worldspawn only */
     vec_t dirtdepth;
     int dirtmode;
+    float dirtangle;
     int minlight_dirt;
     vec_t dist;
     vec_t range;
diff --git a/include/light/light.h b/include/light/light.h
index 9722e353..c123c0c7 100644
--- a/include/light/light.h
+++ b/include/light/light.h
@@ -124,6 +124,7 @@ extern int dirtMode;
 extern float dirtDepth;
 extern float dirtScale;
 extern float dirtGain;
+extern float dirtAngle;
 
 extern qboolean globalDirt;     // apply dirt to all lights (unless they override it)?
 extern qboolean minlightDirt;   // apply dirt to minlight?
@@ -132,6 +133,7 @@ extern qboolean dirtModeSetOnCmdline;
 extern qboolean dirtDepthSetOnCmdline;
 extern qboolean dirtScaleSetOnCmdline;
 extern qboolean dirtGainSetOnCmdline;
+extern qboolean dirtAngleSetOnCmdline;
 
 /*
  * Return space for the lightmap and colourmap at the same time so it can
diff --git a/light/entities.c b/light/entities.c
index 4c53f61c..82cade51 100644
--- a/light/entities.c
+++ b/light/entities.c
@@ -748,6 +748,8 @@ LoadEntities(const bsp2_t *bsp)
 		entity->dirtdepth = atof(com_token);
 	    else if (!strcmp(key, "_dirtmode"))
 		entity->dirtmode = atoi(com_token);
+	    else if (!strcmp(key, "_dirtangle"))
+		entity->dirtangle = atoi(com_token);
 	    else if (!strcmp(key, "_sunlight_dirt"))
 		sunlight_dirt = atoi(com_token);
 	    else if (!strcmp(key, "_sunlight2_dirt"))
@@ -849,6 +851,11 @@ LoadEntities(const bsp2_t *bsp)
 		logprint("Using dirtgain value %f from worldspawn.\n", 
 			dirtGain);
 	    }
+	    if (entity->dirtangle && !dirtAngleSetOnCmdline) {
+		dirtAngle = entity->dirtangle;
+		logprint("Using dirtangle value %f from worldspawn.\n",
+			 dirtAngle);
+	    }
 	    if (entity->dirt == 1) {
 		globalDirt = true;
 		dirty = true;
diff --git a/light/light.c b/light/light.c
index 3251b38a..3f4df767 100644
--- a/light/light.c
+++ b/light/light.c
@@ -43,6 +43,7 @@ int dirtMode = 0;
 float dirtDepth = 128.0f;
 float dirtScale = 1.0f;
 float dirtGain = 1.0f;
+float dirtAngle = 88.0f;
 
 qboolean globalDirt = false;
 qboolean minlightDirt = false;
@@ -52,6 +53,7 @@ qboolean dirtModeSetOnCmdline = false;
 qboolean dirtDepthSetOnCmdline = false;
 qboolean dirtScaleSetOnCmdline = false;
 qboolean dirtGainSetOnCmdline = false;
+qboolean dirtAngleSetOnCmdline = false;
 
 qboolean testFenceTextures = false;
 
@@ -353,6 +355,10 @@ main(int argc, const char **argv)
 		dirtGain = 1.0f;
 	    }
 	    logprint( "Dirtmapping gain set to %.1f\n", dirtGain );
+	} else if ( !strcmp( argv[ i ], "-dirtangle" ) ) {
+	    dirtAngleSetOnCmdline = true;
+	    dirtAngle = atof( argv[ ++i ] );
+	    logprint( "Dirtmapping cone angle set to %.1f\n", dirtAngle );
 	} else if ( !strcmp( argv[ i ], "-fence" ) ) {
 	    testFenceTextures = true;
 	    logprint( "Fence texture tracing enabled on command line\n" );
@@ -373,7 +379,7 @@ main(int argc, const char **argv)
 	printf("usage: light [-threads num] [-extra|-extra4]\n"
 	       "             [-light num] [-addmin] [-anglescale|-anglesense]\n"
 	       "             [-dist n] [-range n] [-gate n] [-lit] [-lux]\n"
-	       "             [-dirt] [-dirtdebug] [-dirtmode n] [-dirtdepth n] [-dirtscale n] [-dirtgain n]\n"
+	       "             [-dirt] [-dirtdebug] [-dirtmode n] [-dirtdepth n] [-dirtscale n] [-dirtgain n] [-dirtangle n]\n"
 	       "             [-soft [n]] [-fence] [-gamma n] [-surflight_subdivide n] [-onlyents] bspfile\n");
 	exit(1);
     }
diff --git a/light/ltface.c b/light/ltface.c
index 7cfb989f..c47b5846 100644
--- a/light/ltface.c
+++ b/light/ltface.c
@@ -1027,7 +1027,6 @@ LightFace_DirtDebug(const lightsurf_t *lightsurf, lightmap_t *lightmaps)
 
 /* Dirtmapping borrowed from q3map2, originally by RaP7oR */
 
-#define DIRT_CONE_ANGLE             88  /* degrees */
 #define DIRT_NUM_ANGLE_STEPS        16
 #define DIRT_NUM_ELEVATION_STEPS    3
 #define DIRT_NUM_VECTORS            ( DIRT_NUM_ANGLE_STEPS * DIRT_NUM_ELEVATION_STEPS )
@@ -1049,9 +1048,17 @@ void SetupDirt( void ) {
     /* note it */
     logprint("--- SetupDirt ---\n" );
 
+    /* clamp dirtAngle */
+    if ( dirtAngle <= 1.0f ) {
+	dirtAngle = 1.0f;
+    }
+    if ( dirtAngle >= 90.0f) {
+	dirtAngle = 90.0f;
+    }
+    
     /* calculate angular steps */
     angleStep = DEG2RAD( 360.0f / DIRT_NUM_ANGLE_STEPS );
-    elevationStep = DEG2RAD( DIRT_CONE_ANGLE / DIRT_NUM_ELEVATION_STEPS );
+    elevationStep = DEG2RAD( dirtAngle / DIRT_NUM_ELEVATION_STEPS );
 
     /* iterate angle */
     angle = 0.0f;
@@ -1159,7 +1166,7 @@ DirtForSample(const dmodel_t *model, const vec3_t origin, const vec3_t normal){
 	for ( i = 0; i < numDirtVectors; i++ ) {
 	    /* get random vector */
 	    angle = Random() * DEG2RAD( 360.0f );
-	    elevation = Random() * DEG2RAD( DIRT_CONE_ANGLE );
+	    elevation = Random() * DEG2RAD( dirtAngle );
 	    temp[ 0 ] = cos( angle ) * sin( elevation );
 	    temp[ 1 ] = sin( angle ) * sin( elevation );
 	    temp[ 2 ] = cos( elevation );
diff --git a/man/light.1 b/man/light.1
index 25fc6008..839881bf 100644
--- a/man/light.1
+++ b/man/light.1
@@ -65,7 +65,7 @@ key. See "_dirt" for more details.
 .IP "\fB\-dirtdebug\fP"
 Implies "-dirt", and renders just the dirtmap against a fullbright background,
 ignoring all lights in the map. Useful for previewing and turning the dirt settings.
-.IP "\fB\-dirtmode n\fP | \fB\-dirtdepth n\fP | \fB\-dirtscale n\fP | \fB\-dirtgain n\fP"
+.IP "\fB\-dirtmode n\fP | \fB\-dirtdepth n\fP | \fB\-dirtscale n\fP | \fB\-dirtgain n\fP | \fB\-dirtangle n\fP"
 Fine-tune the dirtmapping, overriding the corresponding worldspawn keys. See the
 worldspawn keys below.
 .IP "\fB\-fence\fP"
@@ -174,6 +174,10 @@ the dirt fainter, 2.0 would create much darker shadows.
 Exponent used in dirt calculation, default 1. Lower values (e.g. 0.5) make the
 shadows darker and stretch further away from corners.
 
+.IP "\fB""_dirtangle"" ""n""\fP"
+Cone angle in degrees for occlusion testing, default 88. Allowed range 1-90.
+Lower values can avoid unwanted dirt on arches, pipe interiors, etc. 
+
 .IP "\fB""_gamma"" ""n""\fP"
 Adjust brightness of final lightmap. Default 1, >1 is brighter, <1 is darker.