diff --git a/src/r_main.c b/src/r_main.c
index 6e5784f58..8e0989f3b 100644
--- a/src/r_main.c
+++ b/src/r_main.c
@@ -1056,6 +1056,7 @@ void R_RenderPlayerView(player_t *player)
 
 	masks[nummasks - 1].drawsegs[0]		= 0;
 	masks[nummasks - 1].vissprites[0]	= 0;
+	masks[nummasks - 1].viewz = viewz;
 	R_RenderBSPNode((INT32)numnodes - 1);
 	masks[nummasks - 1].drawsegs[1]		= ds_p - drawsegs;
 	masks[nummasks - 1].vissprites[1]	= visspritecount;
@@ -1103,6 +1104,7 @@ void R_RenderPlayerView(player_t *player)
 
 			masks[nummasks - 1].drawsegs[0]		= ds_p - drawsegs;
 			masks[nummasks - 1].vissprites[0]	= visspritecount;
+			masks[nummasks - 1].viewz = viewz;
 			R_RenderBSPNode((INT32)numnodes - 1);
 			masks[nummasks - 1].drawsegs[1]		= ds_p - drawsegs;
 			masks[nummasks - 1].vissprites[1]	= visspritecount;
@@ -1118,6 +1120,7 @@ void R_RenderPlayerView(player_t *player)
 #ifdef FLOORSPLATS
 	R_DrawVisibleFloorSplats();
 #endif
+
 	// draw mid texture and sprite
 	// And now 3D floors/sides!
 	R_DrawMasked(masks, nummasks);
diff --git a/src/r_portal.c b/src/r_portal.c
index 0a0f4777d..b3d363f63 100644
--- a/src/r_portal.c
+++ b/src/r_portal.c
@@ -199,7 +199,15 @@ static void Portal_ClipVisplane (const visplane_t* plane, portal_t* portal)
 
 	for (i = 0; i < end - start; i++)
 	{
-		portal->ceilingclip[i] = plane->top[i + start];
+		if (plane->bottom[i + start] == 0)
+		{
+			portal->ceilingclip[i] = 0;
+			portal->floorclip[i] = 0;
+			continue;
+		}
+
+
+		portal->ceilingclip[i] = plane->top[i + start] - 1;
 		portal->floorclip[i] = plane->bottom[i + start] + 1;
 		portal->frontscale[i] = INT32_MAX;
 	}
diff --git a/src/r_things.c b/src/r_things.c
index f984d75d7..8be926adf 100644
--- a/src/r_things.c
+++ b/src/r_things.c
@@ -1697,9 +1697,7 @@ void R_AddSprites(sector_t *sec, INT32 lightlevel)
 //
 // R_SortVisSprites
 //
-static vissprite_t vsprsortedhead;
-
-void R_SortVisSprites(void)
+static void R_SortVisSprites(vissprite_t* vsprsortedhead, UINT32 start, UINT32 end)
 {
 	UINT32       i, linkedvissprites = 0;
 	vissprite_t *ds, *dsprev, *dsnext, *dsfirst;
@@ -1708,20 +1706,17 @@ void R_SortVisSprites(void)
 	fixed_t      bestscale;
 	INT32        bestdispoffset;
 
-	if (!visspritecount)
-		return;
-
 	unsorted.next = unsorted.prev = &unsorted;
 
-	dsfirst = R_GetVisSprite(0);
+	dsfirst = R_GetVisSprite(start);
 
 	// The first's prev and last's next will be set to
 	// nonsense, but are fixed in a moment
-	for (i = 0, dsnext = dsfirst, ds = NULL; i < visspritecount; i++)
+	for (i = start, dsnext = dsfirst, ds = NULL; i < end; i++)
 	{
 		dsprev = ds;
 		ds = dsnext;
-		if (i < visspritecount - 1) dsnext = R_GetVisSprite(i + 1);
+		if (i < end - 1) dsnext = R_GetVisSprite(i + 1);
 
 		ds->next = dsnext;
 		ds->prev = dsprev;
@@ -1799,8 +1794,8 @@ void R_SortVisSprites(void)
 	}
 
 	// pull the vissprites out by scale
-	vsprsortedhead.next = vsprsortedhead.prev = &vsprsortedhead;
-	for (i = 0; i < visspritecount-linkedvissprites; i++)
+	vsprsortedhead->next = vsprsortedhead->prev = vsprsortedhead;
+	for (i = start; i < end-linkedvissprites; i++)
 	{
 		bestscale = bestdispoffset = INT32_MAX;
 		for (ds = unsorted.next; ds != &unsorted; ds = ds->next)
@@ -1825,10 +1820,10 @@ void R_SortVisSprites(void)
 		}
 		best->next->prev = best->prev;
 		best->prev->next = best->next;
-		best->next = &vsprsortedhead;
-		best->prev = vsprsortedhead.prev;
-		vsprsortedhead.prev->next = best;
-		vsprsortedhead.prev = best;
+		best->next = vsprsortedhead;
+		best->prev = vsprsortedhead->prev;
+		vsprsortedhead->prev->next = best;
+		vsprsortedhead->prev = best;
 	}
 }
 
@@ -1846,6 +1841,7 @@ static void R_CreateDrawNodes(maskcount_t* mask, drawnode_t* head, boolean temps
 	INT32 i, p, best, x1, x2;
 	fixed_t bestdelta, delta;
 	vissprite_t *rover;
+	static vissprite_t vsprsortedhead;
 	drawnode_t *r2;
 	visplane_t *plane;
 	INT32 sintersect;
@@ -1950,10 +1946,12 @@ static void R_CreateDrawNodes(maskcount_t* mask, drawnode_t* head, boolean temps
 	}
 #endif
 
-	if (visspritecount == 0)
+	// No vissprites in this mask?
+	if (mask->vissprites[1] - mask->vissprites[0] == 0)
 		return;
 
-	R_SortVisSprites();
+	R_SortVisSprites(&vsprsortedhead, mask->vissprites[0], mask->vissprites[1]);
+
 	for (rover = vsprsortedhead.prev; rover != &vsprsortedhead; rover = rover->prev)
 	{
 		if (rover->szt > vid.height || rover->sz < 0)
@@ -2436,14 +2434,14 @@ static void R_DrawMaskedList (drawnode_t* head)
 
 void R_DrawMasked(maskcount_t* masks, UINT8 nummasks)
 {
-	drawnode_t heads[nummasks];
+	drawnode_t heads[nummasks];	/**< Drawnode lists; as many as number of views/portals. */
 	INT8 i;
 
 	for (i = 0; i < nummasks; i++)
 	{
 		heads[i].next = heads[i].prev = &heads[i];
-
-		R_CreateDrawNodes(&masks[i], &heads[i], i != 0 ? true : false);
+		viewz = masks[i].viewz;
+		R_CreateDrawNodes(&masks[i], &heads[i], false);
 	}
 
 	for (i = 0; i < nummasks; i++)
@@ -2451,6 +2449,7 @@ void R_DrawMasked(maskcount_t* masks, UINT8 nummasks)
 
 	for (; nummasks > 0; nummasks--)
 	{
+		viewz = masks[nummasks - 1].viewz;
 		R_DrawMaskedList(&heads[nummasks - 1]);
 		R_ClearDrawNodes(&heads[nummasks - 1]);
 	}
diff --git a/src/r_things.h b/src/r_things.h
index 7aa594c79..08a13c1ce 100644
--- a/src/r_things.h
+++ b/src/r_things.h
@@ -45,7 +45,6 @@ extern fixed_t windowbottom;
 
 void R_DrawMaskedColumn(column_t *column);
 void R_DrawFlippedMaskedColumn(column_t *column, INT32 texheight);
-void R_SortVisSprites(void);
 
 //faB: find sprites in wadfile, replace existing, add new ones
 //     (only sprites from namelist are added or replaced)
@@ -65,6 +64,7 @@ typedef struct
 {
 	size_t drawsegs[2];
 	size_t vissprites[2];
+	fixed_t viewz;			/**< View z stored at the time of the BSP traversal for the view/portal. Masked sorting/drawing needs it. */
 } maskcount_t;
 
 void R_DrawMasked(maskcount_t* masks, UINT8 nummasks);