diff --git a/src/p_setup.c b/src/p_setup.c
index a29a6080a..eb8489726 100644
--- a/src/p_setup.c
+++ b/src/p_setup.c
@@ -718,7 +718,6 @@ static void P_LoadRawSectors(UINT8 *data, size_t i)
 		ss->spawn_flr_xoffs = ss->spawn_ceil_xoffs = ss->spawn_flr_yoffs = ss->spawn_ceil_yoffs = 0;
 		ss->floorpic_angle = ss->ceilingpic_angle = 0;
 		ss->spawn_flrpic_angle = ss->spawn_ceilpic_angle = 0;
-		ss->bottommap = ss->midmap = ss->topmap = -1;
 		ss->gravity = NULL;
 		ss->cullheight = NULL;
 		ss->verticalflip = false;
diff --git a/src/p_spec.c b/src/p_spec.c
index 6c359c9cc..698c8f4b1 100644
--- a/src/p_spec.c
+++ b/src/p_spec.c
@@ -6760,7 +6760,7 @@ void P_SpawnSpecials(INT32 fromnetsave)
 
 			case 606: // HACK! Copy colormaps. Just plain colormaps.
 				for (s = -1; (s = P_FindSectorFromLineTag(lines + i, s)) >= 0 ;)
-					sectors[s].midmap = lines[i].frontsector->midmap;
+					sectors[s].extra_colormap = lines[i].frontsector->extra_colormap;
 				break;
 
 #ifdef ESLOPE // Slope copy specials. Handled here for sanity.
diff --git a/src/r_bsp.c b/src/r_bsp.c
index 183def25a..512aab696 100644
--- a/src/r_bsp.c
+++ b/src/r_bsp.c
@@ -234,8 +234,6 @@ static INT32 R_DoorClosed(void)
 sector_t *R_FakeFlat(sector_t *sec, sector_t *tempsec, INT32 *floorlightlevel,
 	INT32 *ceilinglightlevel, boolean back)
 {
-	INT32 mapnum = -1;
-
 	if (floorlightlevel)
 		*floorlightlevel = sec->floorlightsec == -1 ?
 			sec->lightlevel : sectors[sec->floorlightsec].lightlevel;
@@ -244,10 +242,10 @@ sector_t *R_FakeFlat(sector_t *sec, sector_t *tempsec, INT32 *floorlightlevel,
 		*ceilinglightlevel = sec->ceilinglightsec == -1 ?
 			sec->lightlevel : sectors[sec->ceilinglightsec].lightlevel;
 
-	// If the sector has a midmap, it's probably from 280 type
-	if (sec->midmap != -1)
-		mapnum = sec->midmap;
-	else if (sec->heightsec != -1)
+	// if (sec->midmap != -1)
+	//	mapnum = sec->midmap;
+	// In original colormap code, this block did not run if sec->midmap was set
+	if (!sec->extra_colormap && sec->heightsec != -1)
 	{
 		const sector_t *s = &sectors[sec->heightsec];
 		mobj_t *viewmobj = viewplayer->mo;
@@ -271,8 +269,6 @@ sector_t *R_FakeFlat(sector_t *sec, sector_t *tempsec, INT32 *floorlightlevel,
 		tempsec->floorheight = s->floorheight;
 		tempsec->ceilingheight = s->ceilingheight;
 
-		mapnum = s->midmap;
-
 		if ((underwater && (tempsec->  floorheight = sec->floorheight,
 			tempsec->ceilingheight = s->floorheight - 1, !back)) || viewz <= s->floorheight)
 		{ // head-below-floor hack
@@ -298,7 +294,6 @@ sector_t *R_FakeFlat(sector_t *sec, sector_t *tempsec, INT32 *floorlightlevel,
 					tempsec->ceiling_yoffs = s->ceiling_yoffs;
 					tempsec->ceilingpic_angle = s->ceilingpic_angle;
 				}
-				mapnum = s->bottommap;
 			}
 
 			tempsec->lightlevel = s->lightlevel;
@@ -322,8 +317,6 @@ sector_t *R_FakeFlat(sector_t *sec, sector_t *tempsec, INT32 *floorlightlevel,
 			tempsec->floor_yoffs = tempsec->ceiling_yoffs = s->ceiling_yoffs;
 			tempsec->floorpic_angle = tempsec->ceilingpic_angle = s->ceilingpic_angle;
 
-			mapnum = s->topmap;
-
 			if (s->floorpic == skyflatnum) // SKYFIX?
 			{
 				tempsec->ceilingheight = tempsec->floorheight-1;
@@ -354,11 +347,6 @@ sector_t *R_FakeFlat(sector_t *sec, sector_t *tempsec, INT32 *floorlightlevel,
 		sec = tempsec;
 	}
 
-	if (mapnum >= 0 && (size_t)mapnum < num_extra_colormaps)
-		sec->extra_colormap = &extra_colormaps[mapnum];
-	else
-		sec->extra_colormap = NULL;
-
 	return sec;
 }
 
@@ -1342,11 +1330,6 @@ void R_Prep3DFloors(sector_t *sector)
 		sector->lightlist[i].slope = bestslope;
 #endif
 		sec = &sectors[best->secnum];
-		mapnum = sec->midmap;
-		if (mapnum >= 0 && (size_t)mapnum < num_extra_colormaps)
-			sec->extra_colormap = &extra_colormaps[mapnum];
-		else
-			sec->extra_colormap = NULL;
 
 		if (best->flags & FF_NOSHADE)
 		{
diff --git a/src/r_defs.h b/src/r_defs.h
index 15312114a..257e36147 100644
--- a/src/r_defs.h
+++ b/src/r_defs.h
@@ -333,8 +333,6 @@ typedef struct sector_s
 	INT32 floorlightsec, ceilinglightsec;
 	INT32 crumblestate; // used for crumbling and bobbing
 
-	INT32 bottommap, midmap, topmap; // dynamic colormaps
-
 	// list of mobjs that are at least partially in the sector
 	// thinglist is a subset of touching_thinglist
 	struct msecnode_s *touching_thinglist;