diff --git a/src/hardware/hw_main.c b/src/hardware/hw_main.c
index f40f21818..3d55c8ecf 100644
--- a/src/hardware/hw_main.c
+++ b/src/hardware/hw_main.c
@@ -295,7 +295,7 @@ static FUINT HWR_CalcWallLight(FUINT lightnum, seg_t *seg)
 {
 	INT16 finallight = lightnum;
 
-	if (seg != NULL && P_ApplyLightOffsetFine(lightnum))
+	if (seg != NULL && P_ApplyLightOffsetFine(lightnum, seg->frontsector->flags))
 	{
 		finallight += seg->hwLightOffset;
 
@@ -306,11 +306,11 @@ static FUINT HWR_CalcWallLight(FUINT lightnum, seg_t *seg)
 	return (FUINT)finallight;
 }
 
-static FUINT HWR_CalcSlopeLight(FUINT lightnum, pslope_t *slope)
+static FUINT HWR_CalcSlopeLight(FUINT lightnum, pslope_t *slope, sectorflags_t sectorflags)
 {
 	INT16 finallight = lightnum;
 
-	if (slope != NULL && P_ApplyLightOffsetFine(lightnum))
+	if (slope != NULL && P_ApplyLightOffsetFine(lightnum, sectorflags))
 	{
 		finallight += slope->hwLightOffset;
 
@@ -504,7 +504,7 @@ static void HWR_RenderPlane(subsector_t *subsector, extrasubsector_t *xsub, bool
 	for (i = 0, v3d = planeVerts; i < nrPlaneVerts; i++,v3d++,pv++)
 		SETUP3DVERT(v3d, pv->x, pv->y);
 
-	lightlevel = HWR_CalcSlopeLight(lightlevel, slope);
+	lightlevel = HWR_CalcSlopeLight(lightlevel, slope, (FOFsector ? FOFsector : gl_frontsector)->flags);
 	HWR_Lighting(&Surf, lightlevel, planecolormap);
 
 	if (PolyFlags & PF_EnvironmentTrans)
diff --git a/src/p_setup.c b/src/p_setup.c
index 3a98716dc..75ac73f4c 100644
--- a/src/p_setup.c
+++ b/src/p_setup.c
@@ -3482,15 +3482,25 @@ void P_UpdateSegLightOffset(seg_t *li)
 #endif
 }
 
-boolean P_ApplyLightOffset(UINT8 baselightnum)
+boolean P_ApplyLightOffset(UINT8 baselightnum, sectorflags_t sectorflags)
 {
+	if (sectorflags & MSF_FLATLIGHTING)
+	{
+		return false;
+	}
+
 	// Don't apply light offsets at full bright or full dark.
 	// Is in steps of light num .
 	return (baselightnum < LIGHTLEVELS-1 && baselightnum > 0);
 }
 
-boolean P_ApplyLightOffsetFine(UINT8 baselightlevel)
+boolean P_ApplyLightOffsetFine(UINT8 baselightlevel, sectorflags_t sectorflags)
 {
+	if (sectorflags & MSF_FLATLIGHTING)
+	{
+		return false;
+	}
+
 	// Don't apply light offsets at full bright or full dark.
 	// Uses exact light levels for more smoothness.
 	return (baselightlevel < 255 && baselightlevel > 0);
diff --git a/src/p_setup.h b/src/p_setup.h
index e626363f4..8a77fc8dd 100644
--- a/src/p_setup.h
+++ b/src/p_setup.h
@@ -140,8 +140,8 @@ void P_LoadSoundsRange(UINT16 wadnum, UINT16 first, UINT16 num);
 void P_LoadMusicsRange(UINT16 wadnum, UINT16 first, UINT16 num);
 //void P_WriteThings(void);
 void P_UpdateSegLightOffset(seg_t *li);
-boolean P_ApplyLightOffset(UINT8 baselightnum);
-boolean P_ApplyLightOffsetFine(UINT8 baselightlevel);
+boolean P_ApplyLightOffset(UINT8 baselightnum, sectorflags_t sectorflags);
+boolean P_ApplyLightOffsetFine(UINT8 baselightlevel, sectorflags_t sectorflags);
 size_t P_PrecacheLevelFlats(void);
 void P_AllocMapHeader(INT16 i);
 
diff --git a/src/r_bsp.cpp b/src/r_bsp.cpp
index 74b78397d..228c57a86 100644
--- a/src/r_bsp.cpp
+++ b/src/r_bsp.cpp
@@ -977,7 +977,7 @@ static void R_Subsector(size_t num)
 			floorcolormap, NULL, NULL, frontsector->f_slope,
 			R_NoEncore(frontsector, &levelflats[frontsector->floorpic], false),
 			R_IsRipplePlane(frontsector, NULL, false),
-			false
+			false, frontsector->flags
 		);
 	}
 	else
@@ -993,7 +993,7 @@ static void R_Subsector(size_t num)
 			ceilingcolormap, NULL, NULL, frontsector->c_slope,
 			R_NoEncore(frontsector, &levelflats[frontsector->ceilingpic], true),
 			R_IsRipplePlane(frontsector, NULL, true),
-			true
+			true, frontsector->flags
 		);
 	}
 	else
@@ -1041,7 +1041,7 @@ static void R_Subsector(size_t num)
 					*rover->bottomyoffs, *rover->bottomangle, *frontsector->lightlist[light].extra_colormap, rover, NULL, *rover->b_slope,
 					R_NoEncore(rover->master->frontsector, &levelflats[*rover->bottompic], true),
 					R_IsRipplePlane(rover->master->frontsector, rover, true),
-					true
+					true, rover->master->frontsector->flags
 				);
 
 				ffloor[numffloors].slope = *rover->b_slope;
@@ -1075,7 +1075,7 @@ static void R_Subsector(size_t num)
 					*frontsector->lightlist[light].extra_colormap, rover, NULL, *rover->t_slope,
 					R_NoEncore(rover->master->frontsector, &levelflats[*rover->toppic], false),
 					R_IsRipplePlane(rover->master->frontsector, rover, false),
-					false
+					false, rover->master->frontsector->flags
 				);
 
 				ffloor[numffloors].slope = *rover->t_slope;
@@ -1125,7 +1125,7 @@ static void R_Subsector(size_t num)
 					NULL, // will ffloors be slopable eventually?
 					R_NoEncore(polysec, &levelflats[polysec->floorpic], false),
 					false, /* TODO: wet polyobjects? */
-					true
+					true, polysec->flags
 				);
 
 				ffloor[numffloors].height = polysec->floorheight;
@@ -1154,7 +1154,7 @@ static void R_Subsector(size_t num)
 					NULL, // will ffloors be slopable eventually?
 					R_NoEncore(polysec, &levelflats[polysec->ceilingpic], true),
 					false, /* TODO: wet polyobjects? */
-					false
+					false, polysec->flags
 				);
 
 				ffloor[numffloors].polyobj = po;
diff --git a/src/r_plane.c b/src/r_plane.c
index 57de53ea9..0c95023a9 100644
--- a/src/r_plane.c
+++ b/src/r_plane.c
@@ -355,7 +355,7 @@ static visplane_t *new_visplane(unsigned hash)
 visplane_t *R_FindPlane(fixed_t height, INT32 picnum, INT32 lightlevel,
 	fixed_t xoff, fixed_t yoff, angle_t plangle, extracolormap_t *planecolormap,
 	ffloor_t *pfloor, polyobj_t *polyobj, pslope_t *slope, boolean noencore,
-	boolean ripple, boolean reverseLight)
+	boolean ripple, boolean reverseLight, sectorflags_t sectorflags)
 {
 	visplane_t *check;
 	unsigned hash;
@@ -392,7 +392,7 @@ visplane_t *R_FindPlane(fixed_t height, INT32 picnum, INT32 lightlevel,
 		}
 	}
 
-	if (slope != NULL && P_ApplyLightOffset(lightlevel >> LIGHTSEGSHIFT))
+	if (slope != NULL && P_ApplyLightOffset(lightlevel >> LIGHTSEGSHIFT, sectorflags))
 	{
 		if (reverseLight && maplighting.directional == true)
 		{
diff --git a/src/r_plane.h b/src/r_plane.h
index e238878f5..06db26ebf 100644
--- a/src/r_plane.h
+++ b/src/r_plane.h
@@ -88,7 +88,7 @@ void R_ClearFFloorClips (void);
 void R_DrawPlanes(void);
 visplane_t *R_FindPlane(fixed_t height, INT32 picnum, INT32 lightlevel, fixed_t xoff, fixed_t yoff, angle_t plangle,
 	extracolormap_t *planecolormap, ffloor_t *ffloor, polyobj_t *polyobj, pslope_t *slope, boolean noencore,
-	boolean ripple, boolean reverseLight);
+	boolean ripple, boolean reverseLight, sectorflags_t sectorflags);
 visplane_t *R_CheckPlane(visplane_t *pl, INT32 start, INT32 stop);
 void R_ExpandPlane(visplane_t *pl, INT32 start, INT32 stop);
 void R_PlaneBounds(visplane_t *plane);
diff --git a/src/r_segs.cpp b/src/r_segs.cpp
index bb63cd1ad..21b8676c9 100644
--- a/src/r_segs.cpp
+++ b/src/r_segs.cpp
@@ -222,7 +222,7 @@ static void R_RenderMaskedSegLoop(drawseg_t *ds, INT32 x1, INT32 x2, INT32 texnu
 
 			if (rlight->extra_colormap && (rlight->extra_colormap->flags & CMF_FOG))
 				;
-			else if (P_ApplyLightOffset(lightnum))
+			else if (P_ApplyLightOffset(lightnum, frontsector->flags))
 				lightnum += curline->lightOffset;
 
 			rlight->lightnum = lightnum;
@@ -245,7 +245,7 @@ static void R_RenderMaskedSegLoop(drawseg_t *ds, INT32 x1, INT32 x2, INT32 texnu
 			if ((R_CheckColumnFunc(COLDRAWFUNC_FOG) == true)
 				|| (frontsector->extra_colormap && (frontsector->extra_colormap->flags & CMF_FOG)))
 				;
-			else if (P_ApplyLightOffset(lightnum))
+			else if (P_ApplyLightOffset(lightnum, frontsector->flags))
 				lightnum += curline->lightOffset;
 
 			lightnum = R_AdjustLightLevel(lightnum);
@@ -882,7 +882,7 @@ void R_RenderThickSideRange(drawseg_t *ds, INT32 x1, INT32 x2, ffloor_t *pfloor)
 
 			if (pfloor->fofflags & FOF_FOG || rlight->flags & FOF_FOG || (rlight->extra_colormap && (rlight->extra_colormap->flags & CMF_FOG)))
 				;
-			else if (P_ApplyLightOffset(rlight->lightnum))
+			else if (P_ApplyLightOffset(rlight->lightnum, pfloor->master->frontsector->flags))
 				rlight->lightnum += curline->lightOffset;
 
 			p++;
@@ -905,7 +905,7 @@ void R_RenderThickSideRange(drawseg_t *ds, INT32 x1, INT32 x2, ffloor_t *pfloor)
 
 		if (pfloor->fofflags & FOF_FOG || (frontsector->extra_colormap && (frontsector->extra_colormap->flags & CMF_FOG)))
 			;
-		else if (P_ApplyLightOffset(lightnum))
+		else if (P_ApplyLightOffset(lightnum, pfloor->master->frontsector->flags))
 			lightnum += curline->lightOffset;
 
 		lightnum = R_AdjustLightLevel(lightnum);
@@ -1511,7 +1511,7 @@ static void R_RenderSegLoop (void)
 
 				if (dc_lightlist[i].extra_colormap)
 					;
-				else if (P_ApplyLightOffset(lightnum))
+				else if (P_ApplyLightOffset(lightnum, curline->frontsector->flags))
 					lightnum += curline->lightOffset;
 
 				lightnum = R_AdjustLightLevel(lightnum);
@@ -2504,7 +2504,7 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 		// OPTIMIZE: get rid of LIGHTSEGSHIFT globally
 		lightnum = (frontsector->lightlevel >> LIGHTSEGSHIFT);
 
-		if (P_ApplyLightOffset(lightnum))
+		if (P_ApplyLightOffset(lightnum, frontsector->flags))
 			lightnum += curline->lightOffset;
 
 		lightnum = R_AdjustLightLevel(lightnum);
diff --git a/src/r_things.c b/src/r_things.c
index d10c402a3..54fb49d62 100644
--- a/src/r_things.c
+++ b/src/r_things.c
@@ -2295,7 +2295,7 @@ static void R_ProjectSprite(mobj_t *thing)
 
 		lightnum = (lightnum + R_ThingLightLevel(oldthing)) >> LIGHTSEGSHIFT;
 
-		if (maplighting.directional == true)
+		if (maplighting.directional == true && !(thing->subsector->sector->flags & MSF_FLATLIGHTING))
 		{
 			fixed_t extralight = R_GetSpriteDirectionalLighting(papersprite
 					? interp.angle + (ang >= ANGLE_180 ? -ANGLE_90 : ANGLE_90)