diff --git a/src/r_bsp.c b/src/r_bsp.c
index d47c1140c..da9ad6656 100644
--- a/src/r_bsp.c
+++ b/src/r_bsp.c
@@ -374,6 +374,7 @@ static void R_AddLine(seg_t *line)
 	INT32 x1, x2;
 	angle_t angle1, angle2, span, tspan;
 	static sector_t tempsec; // ceiling/water hack
+	sector_t *thissec = R_PointInSubsector(viewx, viewy)->sector;
 
 	if (line->polyseg && !(line->polyseg->flags & POF_RENDERSIDES))
 		return;
@@ -478,21 +479,24 @@ static void R_AddLine(seg_t *line)
 		SLOPEPARAMS( backsector->f_slope, backf1,  backf2,  backsector->floorheight)
 		SLOPEPARAMS( backsector->c_slope, backc1,  backc2,  backsector->ceilingheight)
 #undef SLOPEPARAMS
-		if ((backc1 <= frontf1 && backc2 <= frontf2)
-			|| (backf1 >= frontc1 && backf2 >= frontc2))
+		if (thissec != backsector && thissec != frontsector)
 		{
-			goto clipsolid;
+			if ((backc1 <= frontf1 && backc2 <= frontf2)
+				|| (backf1 >= frontc1 && backf2 >= frontc2))
+			{
+				goto clipsolid;
+			}
+
+			// Check for automap fix. Store in doorclosed for r_segs.c
+			doorclosed = (backc1 <= backf1 && backc2 <= backf2
+			&& ((backc1 >= frontc1 && backc2 >= frontc2) || curline->sidedef->toptexture)
+			&& ((backf1 <= frontf1 && backf2 >= frontf2) || curline->sidedef->bottomtexture)
+			&& (backsector->ceilingpic != skyflatnum || frontsector->ceilingpic != skyflatnum));
+
+			if (doorclosed)
+				goto clipsolid;
 		}
 
-		// Check for automap fix. Store in doorclosed for r_segs.c
-		doorclosed = (backc1 <= backf1 && backc2 <= backf2
-		&& ((backc1 >= frontc1 && backc2 >= frontc2) || curline->sidedef->toptexture)
-		&& ((backf1 <= frontf1 && backf2 >= frontf2) || curline->sidedef->bottomtexture)
-		&& (backsector->ceilingpic != skyflatnum || frontsector->ceilingpic != skyflatnum));
-
-		if (doorclosed)
-			goto clipsolid;
-
 		// Window.
 		if (backc1 != frontc1 || backc2 != frontc2
 			|| backf1 != frontf1 || backf2 != frontf2)
@@ -503,21 +507,24 @@ static void R_AddLine(seg_t *line)
 	else
 #endif
 	{
-		if (backsector->ceilingheight <= frontsector->floorheight
-			|| backsector->floorheight >= frontsector->ceilingheight)
+		if (thissec != backsector && thissec != frontsector)
 		{
-			goto clipsolid;
+			if (backsector->ceilingheight <= frontsector->floorheight
+				|| backsector->floorheight >= frontsector->ceilingheight)
+			{
+				goto clipsolid;
+			}
+
+			// Check for automap fix. Store in doorclosed for r_segs.c
+			doorclosed = (backsector->ceilingheight <= backsector->floorheight
+			&& (backsector->ceilingheight >= frontsector->ceilingheight || curline->sidedef->toptexture)
+			&& (backsector->floorheight <= frontsector->floorheight || curline->sidedef->bottomtexture)
+			&& (backsector->ceilingpic != skyflatnum || frontsector->ceilingpic != skyflatnum));
+
+			if (doorclosed)
+				goto clipsolid;
 		}
 
-		// Check for automap fix. Store in doorclosed for r_segs.c
-		doorclosed = (backsector->ceilingheight <= backsector->floorheight
-		&& (backsector->ceilingheight >= frontsector->ceilingheight || curline->sidedef->toptexture)
-		&& (backsector->floorheight <= frontsector->floorheight || curline->sidedef->bottomtexture)
-		&& (backsector->ceilingpic != skyflatnum || frontsector->ceilingpic != skyflatnum));
-
-		if (doorclosed)
-			goto clipsolid;
-
 		// Window.
 		if (backsector->ceilingheight != frontsector->ceilingheight
 			|| backsector->floorheight != frontsector->floorheight)
diff --git a/src/r_segs.c b/src/r_segs.c
index 11287f16d..84bb119fd 100644
--- a/src/r_segs.c
+++ b/src/r_segs.c
@@ -2020,6 +2020,8 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 	{
 		// two sided line
 
+		sector_t *thissec = R_PointInSubsector(viewx, viewy)->sector;
+
 #ifdef ESLOPE
 		if (backsector->c_slope) {
 			worldhigh = P_GetZAt(backsector->c_slope, segleft.x, segleft.y) - viewz;
@@ -2113,52 +2115,55 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 			// ds_p->sprtopclip = screenheightarray;
 		}
 
-#ifdef ESLOPE
-		if (worldhigh <= worldbottom && worldhighslope <= worldbottomslope)
-#else
-		if (worldhigh <= worldbottom)
-#endif
-		{
-			ds_p->sprbottomclip = negonearray;
-			ds_p->bsilheight = INT32_MAX;
-			ds_p->silhouette |= SIL_BOTTOM;
-		}
-
-#ifdef ESLOPE
-		if (worldlow >= worldtop && worldlowslope >= worldtopslope)
-#else
-		if (worldlow >= worldtop)
-#endif
-		{
-			ds_p->sprtopclip = screenheightarray;
-			ds_p->tsilheight = INT32_MIN;
-			ds_p->silhouette |= SIL_TOP;
-		}
-
-		//SoM: 3/25/2000: This code fixes an automap bug that didn't check
-		// frontsector->ceiling and backsector->floor to see if a door was closed.
-		// Without the following code, sprites get displayed behind closed doors.
+		if (thissec != frontsector && thissec != backsector)
 		{
 #ifdef ESLOPE
-			if (doorclosed || (worldhigh <= worldbottom && worldhighslope <= worldbottomslope))
+			if (worldhigh <= worldbottom && worldhighslope <= worldbottomslope)
 #else
-			if (doorclosed || backsector->ceilingheight <= frontsector->floorheight)
+			if (worldhigh <= worldbottom)
 #endif
 			{
 				ds_p->sprbottomclip = negonearray;
 				ds_p->bsilheight = INT32_MAX;
 				ds_p->silhouette |= SIL_BOTTOM;
 			}
+
 #ifdef ESLOPE
-			if (doorclosed || (worldlow >= worldtop && worldlowslope >= worldtopslope))
+			if (worldlow >= worldtop && worldlowslope >= worldtopslope)
 #else
-			if (doorclosed || backsector->floorheight >= frontsector->ceilingheight)
+			if (worldlow >= worldtop)
 #endif
-			{                   // killough 1/17/98, 2/8/98
+			{
 				ds_p->sprtopclip = screenheightarray;
 				ds_p->tsilheight = INT32_MIN;
 				ds_p->silhouette |= SIL_TOP;
 			}
+
+			//SoM: 3/25/2000: This code fixes an automap bug that didn't check
+			// frontsector->ceiling and backsector->floor to see if a door was closed.
+			// Without the following code, sprites get displayed behind closed doors.
+			{
+#ifdef ESLOPE
+				if (doorclosed || (worldhigh <= worldbottom && worldhighslope <= worldbottomslope))
+#else
+				if (doorclosed || backsector->ceilingheight <= frontsector->floorheight)
+#endif
+				{
+					ds_p->sprbottomclip = negonearray;
+					ds_p->bsilheight = INT32_MAX;
+					ds_p->silhouette |= SIL_BOTTOM;
+				}
+#ifdef ESLOPE
+				if (doorclosed || (worldlow >= worldtop && worldlowslope >= worldtopslope))
+#else
+				if (doorclosed || backsector->floorheight >= frontsector->ceilingheight)
+#endif
+				{                   // killough 1/17/98, 2/8/98
+					ds_p->sprtopclip = screenheightarray;
+					ds_p->tsilheight = INT32_MIN;
+					ds_p->silhouette |= SIL_TOP;
+				}
+			}
 		}
 
 		if (worldlow != worldbottom