diff --git a/.travis.yml b/.travis.yml
index e3408cf6f..d728758ed 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -98,7 +98,7 @@ matrix:
               - p7zip-full
               - gcc-6
           compiler: gcc-6
-          env: WFLAGS="-Wno-error=tautological-compare"
+          env: WFLAGS="-Wno-tautological-compare"
           #gcc-6 (Ubuntu 6.1.1-3ubuntu11~14.04.1) 6.1.1 20160511
         - os: linux
           compiler: clang
@@ -213,7 +213,7 @@ before_script:
   - 7z x $HOME/srb2_cache/SRB2-v2115-assets-2.7z -oassets
   - mkdir build
   - cd build
-  - export CFLAGS="-Wall -W $WFLAGS"
+  - export CFLAGS="-Wall -W -Werror $WFLAGS"
   - export CCACHE_COMPRESS=true
   - cmake .. -DCMAKE_BUILD_TYPE=Release
 
diff --git a/src/p_floor.c b/src/p_floor.c
index 1c396c877..911213014 100644
--- a/src/p_floor.c
+++ b/src/p_floor.c
@@ -1163,7 +1163,7 @@ void T_SpikeSector(levelspecthink_t *spikes)
 
 	node = spikes->sector->touching_thinglist; // things touching this sector
 
-	for (; node; node = node->m_snext)
+	for (; node; node = node->m_thinglist_next)
 	{
 		thing = node->m_thing;
 		if (!thing->player)
@@ -1316,7 +1316,7 @@ void T_BridgeThinker(levelspecthink_t *bridge)
 			controlsec = &sectors[k];
 
 			// Is a player standing on me?
-			for (node = sector->touching_thinglist; node; node = node->m_snext)
+			for (node = sector->touching_thinglist; node; node = node->m_thinglist_next)
 			{
 				thing = node->m_thing;
 
@@ -1739,7 +1739,7 @@ wegotit:
 static mobj_t *SearchMarioNode(msecnode_t *node)
 {
 	mobj_t *thing = NULL;
-	for (; node; node = node->m_snext)
+	for (; node; node = node->m_thinglist_next)
 	{
 		// Things which should NEVER be ejected from a MarioBlock, by type.
 		switch (node->m_thing->type)
@@ -2003,7 +2003,7 @@ void T_NoEnemiesSector(levelspecthink_t *nobaddies)
 						goto foundenemy;
 					}
 
-					node = node->m_snext;
+					node = node->m_thinglist_next;
 				}
 			}
 		}
@@ -2288,7 +2288,7 @@ void T_RaiseSector(levelspecthink_t *raise)
 		sector = &sectors[i];
 
 		// Is a player standing on me?
-		for (node = sector->touching_thinglist; node; node = node->m_snext)
+		for (node = sector->touching_thinglist; node; node = node->m_thinglist_next)
 		{
 			thing = node->m_thing;
 
diff --git a/src/p_map.c b/src/p_map.c
index 71adf2e16..44df30018 100644
--- a/src/p_map.c
+++ b/src/p_map.c
@@ -3365,7 +3365,7 @@ boolean P_CheckSector(sector_t *sector, boolean crunch)
 		for (i = 0; i < sector->numattached; i++)
 		{
 			sec = &sectors[sector->attached[i]];
-			for (n = sec->touching_thinglist; n; n = n->m_snext)
+			for (n = sec->touching_thinglist; n; n = n->m_thinglist_next)
 				n->visited = false;
 
 			sec->moved = true;
@@ -3377,7 +3377,7 @@ boolean P_CheckSector(sector_t *sector, boolean crunch)
 
 			do
 			{
-				for (n = sec->touching_thinglist; n; n = n->m_snext)
+				for (n = sec->touching_thinglist; n; n = n->m_thinglist_next)
 				if (!n->visited)
 				{
 					n->visited = true;
@@ -3398,12 +3398,12 @@ boolean P_CheckSector(sector_t *sector, boolean crunch)
 	// Mark all things invalid
 	sector->moved = true;
 
-	for (n = sector->touching_thinglist; n; n = n->m_snext)
+	for (n = sector->touching_thinglist; n; n = n->m_thinglist_next)
 		n->visited = false;
 
 	do
 	{
-		for (n = sector->touching_thinglist; n; n = n->m_snext) // go through list
+		for (n = sector->touching_thinglist; n; n = n->m_thinglist_next) // go through list
 			if (!n->visited) // unprocessed thing found
 			{
 				n->visited = true; // mark thing as processed
@@ -3427,7 +3427,7 @@ boolean P_CheckSector(sector_t *sector, boolean crunch)
 		for (i = 0; i < sector->numattached; i++)
 		{
 			sec = &sectors[sector->attached[i]];
-			for (n = sec->touching_thinglist; n; n = n->m_snext)
+			for (n = sec->touching_thinglist; n; n = n->m_thinglist_next)
 				n->visited = false;
 
 			sec->moved = true;
@@ -3439,7 +3439,7 @@ boolean P_CheckSector(sector_t *sector, boolean crunch)
 
 			do
 			{
-				for (n = sec->touching_thinglist; n; n = n->m_snext)
+				for (n = sec->touching_thinglist; n; n = n->m_thinglist_next)
 				if (!n->visited)
 				{
 					n->visited = true;
@@ -3457,12 +3457,12 @@ boolean P_CheckSector(sector_t *sector, boolean crunch)
 	// Mark all things invalid
 	sector->moved = true;
 
-	for (n = sector->touching_thinglist; n; n = n->m_snext)
+	for (n = sector->touching_thinglist; n; n = n->m_thinglist_next)
 		n->visited = false;
 
 	do
 	{
-		for (n = sector->touching_thinglist; n; n = n->m_snext) // go through list
+		for (n = sector->touching_thinglist; n; n = n->m_thinglist_next) // go through list
 			if (!n->visited) // unprocessed thing found
 			{
 				n->visited = true; // mark thing as processed
@@ -3502,7 +3502,7 @@ static msecnode_t *P_GetSecnode(void)
 	if (headsecnode)
 	{
 		node = headsecnode;
-		headsecnode = headsecnode->m_snext;
+		headsecnode = headsecnode->m_thinglist_next;
 	}
 	else
 		node = Z_Calloc(sizeof (*node), PU_LEVEL, NULL);
@@ -3516,7 +3516,7 @@ static mprecipsecnode_t *P_GetPrecipSecnode(void)
 	if (headprecipsecnode)
 	{
 		node = headprecipsecnode;
-		headprecipsecnode = headprecipsecnode->m_snext;
+		headprecipsecnode = headprecipsecnode->m_thinglist_next;
 	}
 	else
 		node = Z_Calloc(sizeof (*node), PU_LEVEL, NULL);
@@ -3527,14 +3527,14 @@ static mprecipsecnode_t *P_GetPrecipSecnode(void)
 
 static inline void P_PutSecnode(msecnode_t *node)
 {
-	node->m_snext = headsecnode;
+	node->m_thinglist_next = headsecnode;
 	headsecnode = node;
 }
 
 // Tails 08-25-2002
 static inline void P_PutPrecipSecnode(mprecipsecnode_t *node)
 {
-	node->m_snext = headprecipsecnode;
+	node->m_thinglist_next = headprecipsecnode;
 	headprecipsecnode = node;
 }
 
@@ -3555,7 +3555,7 @@ static msecnode_t *P_AddSecnode(sector_t *s, mobj_t *thing, msecnode_t *nextnode
 			node->m_thing = thing; // Yes. Setting m_thing says 'keep it'.
 			return nextnode;
 		}
-		node = node->m_tnext;
+		node = node->m_sectorlist_next;
 	}
 
 	// Couldn't find an existing node for this sector. Add one at the head
@@ -3568,17 +3568,17 @@ static msecnode_t *P_AddSecnode(sector_t *s, mobj_t *thing, msecnode_t *nextnode
 
 	node->m_sector = s; // sector
 	node->m_thing = thing; // mobj
-	node->m_tprev = NULL; // prev node on Thing thread
-	node->m_tnext = nextnode; // next node on Thing thread
+	node->m_sectorlist_prev = NULL; // prev node on Thing thread
+	node->m_sectorlist_next = nextnode; // next node on Thing thread
 	if (nextnode)
-		nextnode->m_tprev = node; // set back link on Thing
+		nextnode->m_sectorlist_prev = node; // set back link on Thing
 
 	// Add new node at head of sector thread starting at s->touching_thinglist
 
-	node->m_sprev = NULL; // prev node on sector thread
-	node->m_snext = s->touching_thinglist; // next node on sector thread
+	node->m_thinglist_prev = NULL; // prev node on sector thread
+	node->m_thinglist_next = s->touching_thinglist; // next node on sector thread
 	if (s->touching_thinglist)
-		node->m_snext->m_sprev = node;
+		node->m_thinglist_next->m_thinglist_prev = node;
 	s->touching_thinglist = node;
 	return node;
 }
@@ -3596,7 +3596,7 @@ static mprecipsecnode_t *P_AddPrecipSecnode(sector_t *s, precipmobj_t *thing, mp
 			node->m_thing = thing; // Yes. Setting m_thing says 'keep it'.
 			return nextnode;
 		}
-		node = node->m_tnext;
+		node = node->m_sectorlist_next;
 	}
 
 	// Couldn't find an existing node for this sector. Add one at the head
@@ -3609,17 +3609,17 @@ static mprecipsecnode_t *P_AddPrecipSecnode(sector_t *s, precipmobj_t *thing, mp
 
 	node->m_sector = s; // sector
 	node->m_thing = thing; // mobj
-	node->m_tprev = NULL; // prev node on Thing thread
-	node->m_tnext = nextnode; // next node on Thing thread
+	node->m_sectorlist_prev = NULL; // prev node on Thing thread
+	node->m_sectorlist_next = nextnode; // next node on Thing thread
 	if (nextnode)
-		nextnode->m_tprev = node; // set back link on Thing
+		nextnode->m_sectorlist_prev = node; // set back link on Thing
 
 	// Add new node at head of sector thread starting at s->touching_thinglist
 
-	node->m_sprev = NULL; // prev node on sector thread
-	node->m_snext = s->touching_preciplist; // next node on sector thread
+	node->m_thinglist_prev = NULL; // prev node on sector thread
+	node->m_thinglist_next = s->touching_preciplist; // next node on sector thread
 	if (s->touching_preciplist)
-		node->m_snext->m_sprev = node;
+		node->m_thinglist_next->m_thinglist_prev = node;
 	s->touching_preciplist = node;
 	return node;
 }
@@ -3641,24 +3641,24 @@ static msecnode_t *P_DelSecnode(msecnode_t *node)
 	// Unlink from the Thing thread. The Thing thread begins at
 	// sector_list and not from mobj_t->touching_sectorlist.
 
-	tp = node->m_tprev;
-	tn = node->m_tnext;
+	tp = node->m_sectorlist_prev;
+	tn = node->m_sectorlist_next;
 	if (tp)
-		tp->m_tnext = tn;
+		tp->m_sectorlist_next = tn;
 	if (tn)
-		tn->m_tprev = tp;
+		tn->m_sectorlist_prev = tp;
 
 	// Unlink from the sector thread. This thread begins at
 	// sector_t->touching_thinglist.
 
-	sp = node->m_sprev;
-	sn = node->m_snext;
+	sp = node->m_thinglist_prev;
+	sn = node->m_thinglist_next;
 	if (sp)
-		sp->m_snext = sn;
+		sp->m_thinglist_next = sn;
 	else
 		node->m_sector->touching_thinglist = sn;
 	if (sn)
-		sn->m_sprev = sp;
+		sn->m_thinglist_prev = sp;
 
 	// Return this node to the freelist
 
@@ -3680,24 +3680,24 @@ static mprecipsecnode_t *P_DelPrecipSecnode(mprecipsecnode_t *node)
 	// Unlink from the Thing thread. The Thing thread begins at
 	// sector_list and not from mobj_t->touching_sectorlist.
 
-	tp = node->m_tprev;
-	tn = node->m_tnext;
+	tp = node->m_sectorlist_prev;
+	tn = node->m_sectorlist_next;
 	if (tp)
-		tp->m_tnext = tn;
+		tp->m_sectorlist_next = tn;
 	if (tn)
-		tn->m_tprev = tp;
+		tn->m_sectorlist_prev = tp;
 
 	// Unlink from the sector thread. This thread begins at
 	// sector_t->touching_thinglist.
 
-	sp = node->m_sprev;
-	sn = node->m_snext;
+	sp = node->m_thinglist_prev;
+	sn = node->m_thinglist_next;
 	if (sp)
-		sp->m_snext = sn;
+		sp->m_thinglist_next = sn;
 	else
 		node->m_sector->touching_preciplist = sn;
 	if (sn)
-		sn->m_sprev = sp;
+		sn->m_thinglist_prev = sp;
 
 	// Return this node to the freelist
 
@@ -3812,7 +3812,7 @@ void P_CreateSecNodeList(mobj_t *thing, fixed_t x, fixed_t y)
 	while (node)
 	{
 		node->m_thing = NULL;
-		node = node->m_tnext;
+		node = node->m_sectorlist_next;
 	}
 
 	P_SetTarget(&tmthing, thing);
@@ -3850,11 +3850,11 @@ void P_CreateSecNodeList(mobj_t *thing, fixed_t x, fixed_t y)
 		if (!node->m_thing)
 		{
 			if (node == sector_list)
-				sector_list = node->m_tnext;
+				sector_list = node->m_sectorlist_next;
 			node = P_DelSecnode(node);
 		}
 		else
-			node = node->m_tnext;
+			node = node->m_sectorlist_next;
 	}
 
 	/* cph -
@@ -3895,7 +3895,7 @@ void P_CreatePrecipSecNodeList(precipmobj_t *thing,fixed_t x,fixed_t y)
 	while (node)
 	{
 		node->m_thing = NULL;
-		node = node->m_tnext;
+		node = node->m_sectorlist_next;
 	}
 
 	tmprecipthing = thing;
@@ -3929,11 +3929,11 @@ void P_CreatePrecipSecNodeList(precipmobj_t *thing,fixed_t x,fixed_t y)
 		if (!node->m_thing)
 		{
 			if (node == precipsector_list)
-				precipsector_list = node->m_tnext;
+				precipsector_list = node->m_sectorlist_next;
 			node = P_DelPrecipSecnode(node);
 		}
 		else
-			node = node->m_tnext;
+			node = node->m_sectorlist_next;
 	}
 
 	/* cph -
diff --git a/src/p_mobj.c b/src/p_mobj.c
index 68fb1696f..adfe319c6 100644
--- a/src/p_mobj.c
+++ b/src/p_mobj.c
@@ -1530,7 +1530,7 @@ static void P_PushableCheckBustables(mobj_t *mo)
 	mo->y += mo->momy;
 	P_SetThingPosition(mo);
 
-	for (node = mo->touching_sectorlist; node; node = node->m_snext)
+	for (node = mo->touching_sectorlist; node; node = node->m_sectorlist_next)
 	{
 		if (!node->m_sector)
 			break;
@@ -2013,12 +2013,14 @@ static void P_AdjustMobjFloorZ_FFloors(mobj_t *mo, sector_t *sector, UINT8 motyp
 		delta1 = mo->z - (bottomheight + ((topheight - bottomheight)/2));
 		delta2 = thingtop - (bottomheight + ((topheight - bottomheight)/2));
 		if (topheight > mo->floorz && abs(delta1) < abs(delta2)
-			&& !(rover->flags & FF_REVERSEPLATFORM))
+			&& !(rover->flags & FF_REVERSEPLATFORM)
+			&& ((P_MobjFlip(mo)*mo->momz > 0) || (!(rover->flags & FF_PLATFORM)))) // In reverse gravity, only clip for FOFs that are intangible from their bottom (the "top" you're falling through) if you're coming from above ("below" in your frame of reference)
 		{
 			mo->floorz = topheight;
 		}
 		if (bottomheight < mo->ceilingz && abs(delta1) >= abs(delta2)
-			&& !(rover->flags & FF_PLATFORM))
+			&& !(rover->flags & FF_PLATFORM)
+			&& ((P_MobjFlip(mo)*mo->momz > 0) || (!(rover->flags & FF_REVERSEPLATFORM)))) // In normal gravity, only clip for FOFs that are intangible from the top if you're coming from below
 		{
 			mo->ceilingz = bottomheight;
 		}
@@ -2703,7 +2705,7 @@ static void P_PlayerZMovement(mobj_t *mo)
 					msecnode_t *node;
 					boolean stopmovecut = false;
 
-					for (node = mo->touching_sectorlist; node; node = node->m_snext)
+					for (node = mo->touching_sectorlist; node; node = node->m_sectorlist_next)
 					{
 						sector_t *sec = node->m_sector;
 						subsector_t *newsubsec;
@@ -2880,7 +2882,7 @@ nightsdone:
 			if (CheckForMarioBlocks && !(netgame && mo->player->spectator)) // Only let the player punch
 			{
 				// Search the touching sectors, from side-to-side...
-				for (node = mo->touching_sectorlist; node; node = node->m_snext)
+				for (node = mo->touching_sectorlist; node; node = node->m_sectorlist_next)
 				{
 					ffloor_t *rover;
 					if (!node->m_sector->ffloors)
@@ -3648,7 +3650,7 @@ static void P_PlayerMobjThinker(mobj_t *mobj)
 	if (!(netgame && mobj->player->spectator))
 	{
 		// Crumbling platforms
-		for (node = mobj->touching_sectorlist; node; node = node->m_snext)
+		for (node = mobj->touching_sectorlist; node; node = node->m_sectorlist_next)
 		{
 			fixed_t topheight, bottomheight;
 			ffloor_t *rover;
@@ -3673,7 +3675,7 @@ static void P_PlayerMobjThinker(mobj_t *mobj)
 	{
 		boolean thereiswater = false;
 
-		for (node = mobj->touching_sectorlist; node; node = node->m_snext)
+		for (node = mobj->touching_sectorlist; node; node = node->m_sectorlist_next)
 		{
 			if (node->m_sector->ffloors)
 			{
@@ -3694,7 +3696,7 @@ static void P_PlayerMobjThinker(mobj_t *mobj)
 		}
 		if (thereiswater)
 		{
-			for (node = mobj->touching_sectorlist; node; node = node->m_snext)
+			for (node = mobj->touching_sectorlist; node; node = node->m_sectorlist_next)
 			{
 				if (node->m_sector->ffloors)
 				{
@@ -3807,7 +3809,7 @@ void P_RecalcPrecipInSector(sector_t *sector)
 
 	sector->moved = true; // Recalc lighting and things too, maybe
 
-	for (psecnode = sector->touching_preciplist; psecnode; psecnode = psecnode->m_snext)
+	for (psecnode = sector->touching_preciplist; psecnode; psecnode = psecnode->m_thinglist_next)
 		CalculatePrecipFloor(psecnode->m_thing);
 }
 
diff --git a/src/p_setup.c b/src/p_setup.c
index b36bf0b80..e56c44c70 100644
--- a/src/p_setup.c
+++ b/src/p_setup.c
@@ -1931,10 +1931,18 @@ static void P_GroupLines(void)
 	// allocate linebuffers for each sector
 	for (i = 0, sector = sectors; i < numsectors; i++, sector++)
 	{
-		sector->lines = Z_Calloc(sector->linecount * sizeof(line_t*), PU_LEVEL, NULL);
+		if (sector->linecount == 0) // no lines found?
+		{
+			sector->lines = NULL;
+			CONS_Debug(DBG_SETUP, "P_GroupLines: sector %s has no lines\n", sizeu1(i));
+		}
+		else
+		{
+			sector->lines = Z_Calloc(sector->linecount * sizeof(line_t*), PU_LEVEL, NULL);
 
-		// zero the count, since we'll later use this to track how many we've recorded
-		sector->linecount = 0;
+			// zero the count, since we'll later use this to track how many we've recorded
+			sector->linecount = 0;
+		}
 	}
 
 	// iterate through lines, assigning them to sectors' linebuffers,
@@ -1952,11 +1960,14 @@ static void P_GroupLines(void)
 	{
 		M_ClearBox(bbox);
 
-		for (j = 0; j < sector->linecount; j++)
+		if (sector->linecount != 0)
 		{
-			li = sector->lines[j];
-			M_AddToBox(bbox, li->v1->x, li->v1->y);
-			M_AddToBox(bbox, li->v2->x, li->v2->y);
+			for (j = 0; j < sector->linecount; j++)
+			{
+				li = sector->lines[j];
+				M_AddToBox(bbox, li->v1->x, li->v1->y);
+				M_AddToBox(bbox, li->v2->x, li->v2->y);
+			}
 		}
 
 		// set the degenmobj_t to the middle of the bounding box
@@ -1966,6 +1977,35 @@ static void P_GroupLines(void)
 	}
 }
 
+//
+// P_LoadReject
+//
+// Detect if the REJECT lump is valid,
+// if not, rejectmatrix will be NULL
+static void P_LoadReject(lumpnum_t lumpnum)
+{
+	size_t count;
+	const char *lumpname = W_CheckNameForNum(lumpnum);
+
+	// Check if the lump exists, and if it's named "REJECT"
+	if (!lumpname || memcmp(lumpname, "REJECT\0\0", 8) != 0)
+	{
+		rejectmatrix = NULL;
+		CONS_Debug(DBG_SETUP, "P_LoadReject: No valid REJECT lump found\n");
+		return;
+	}
+
+	count = W_LumpLength(lumpnum);
+
+	if (!count) // zero length, someone probably used ZDBSP
+	{
+		rejectmatrix = NULL;
+		CONS_Debug(DBG_SETUP, "P_LoadReject: REJECT lump has size 0, will not be loaded\n");
+	}
+	else
+		rejectmatrix = W_CacheLumpNum(lumpnum, PU_LEVEL);
+}
+
 #if 0
 static char *levellumps[] =
 {
@@ -2574,7 +2614,7 @@ boolean P_SetupLevel(boolean skipprecip)
 	P_LoadSubsectors(lastloadedmaplumpnum + ML_SSECTORS);
 	P_LoadNodes(lastloadedmaplumpnum + ML_NODES);
 	P_LoadSegs(lastloadedmaplumpnum + ML_SEGS);
-	rejectmatrix = W_CacheLumpNum(lastloadedmaplumpnum + ML_REJECT, PU_LEVEL);
+	P_LoadReject(lastloadedmaplumpnum + ML_REJECT);
 	P_GroupLines();
 
 	numdmstarts = numredctfstarts = numbluectfstarts = 0;
diff --git a/src/p_sight.c b/src/p_sight.c
index 14c1c945f..bd6ab4d73 100644
--- a/src/p_sight.c
+++ b/src/p_sight.c
@@ -325,9 +325,12 @@ boolean P_CheckSight(mobj_t *t1, mobj_t *t2)
 	s2 = t2->subsector->sector;
 	pnum = (s1-sectors)*numsectors + (s2-sectors);
 
-	// Check in REJECT table.
-	if (rejectmatrix[pnum>>3] & (1 << (pnum&7))) // can't possibly be connected
-		return false;
+	if (rejectmatrix != NULL)
+	{
+		// Check in REJECT table.
+		if (rejectmatrix[pnum>>3] & (1 << (pnum&7))) // can't possibly be connected
+			return false;
+	}
 
 	// killough 11/98: shortcut for melee situations
 	// same subsector? obviously visible
diff --git a/src/p_spec.c b/src/p_spec.c
index 9e4c3f079..0bd530279 100644
--- a/src/p_spec.c
+++ b/src/p_spec.c
@@ -1642,7 +1642,7 @@ boolean P_RunTriggerLinedef(line_t *triggerline, mobj_t *actor, sector_t *caller
 			mo = node->m_thing;
 			if (mo->flags & MF_PUSHABLE)
 				numpush++;
-			node = node->m_snext;
+			node = node->m_thinglist_next;
 		}
 
 		if (triggerline->flags & ML_NOCLIMB) // Need at least or more
@@ -3144,7 +3144,7 @@ void P_SetupSignExit(player_t *player)
 	thinker_t *think;
 	INT32 numfound = 0;
 
-	for (; node; node = node->m_snext)
+	for (; node; node = node->m_thinglist_next)
 	{
 		thing = node->m_thing;
 		if (thing->type != MT_SIGN)
@@ -3308,7 +3308,7 @@ sector_t *P_PlayerTouchingSectorSpecial(player_t *player, INT32 section, INT32 n
 		return rover->master->frontsector;
 	}
 
-	for (node = player->mo->touching_sectorlist; node; node = node->m_snext)
+	for (node = player->mo->touching_sectorlist; node; node = node->m_sectorlist_next)
 	{
 		if (GETSECSPECIAL(node->m_sector->special, section) == number)
 		{
@@ -4657,7 +4657,7 @@ void P_PlayerInSpecialSector(player_t *player)
 		P_RunSpecialSectorCheck(player, sector);
 
 	// Iterate through touching_sectorlist
-	for (node = player->mo->touching_sectorlist; node; node = node->m_snext)
+	for (node = player->mo->touching_sectorlist; node; node = node->m_sectorlist_next)
 	{
 		sector = node->m_sector;
 
@@ -5308,7 +5308,7 @@ void T_LaserFlash(laserthink_t *flash)
 	S_StartSound(&sector->soundorg, sfx_laser);
 
 	// Seek out objects to DESTROY! MUAHAHHAHAHAA!!!*cough*
-	for (node = sector->touching_thinglist; node && node->m_thing; node = node->m_snext)
+	for (node = sector->touching_thinglist; node && node->m_thing; node = node->m_thinglist_next)
 	{
 		thing = node->m_thing;
 
@@ -6579,7 +6579,7 @@ void T_Scroll(scroll_t *s)
 					sector_t *psec;
 					psec = sectors + sect;
 
-					for (node = psec->touching_thinglist; node; node = node->m_snext)
+					for (node = psec->touching_thinglist; node; node = node->m_thinglist_next)
 					{
 						thing = node->m_thing;
 
@@ -6601,7 +6601,7 @@ void T_Scroll(scroll_t *s)
 
 			if (!is3dblock)
 			{
-				for (node = sec->touching_thinglist; node; node = node->m_snext)
+				for (node = sec->touching_thinglist; node; node = node->m_thinglist_next)
 				{
 					thing = node->m_thing;
 
@@ -6642,7 +6642,7 @@ void T_Scroll(scroll_t *s)
 					sector_t *psec;
 					psec = sectors + sect;
 
-					for (node = psec->touching_thinglist; node; node = node->m_snext)
+					for (node = psec->touching_thinglist; node; node = node->m_thinglist_next)
 					{
 						thing = node->m_thing;
 
@@ -6664,7 +6664,7 @@ void T_Scroll(scroll_t *s)
 
 			if (!is3dblock)
 			{
-				for (node = sec->touching_thinglist; node; node = node->m_snext)
+				for (node = sec->touching_thinglist; node; node = node->m_thinglist_next)
 				{
 					thing = node->m_thing;
 
@@ -7014,7 +7014,7 @@ void T_Friction(friction_t *f)
 			{
 				if (thing->floorz != P_GetSpecialTopZ(thing, referrer, sec))
 				{
-					node = node->m_snext;
+					node = node->m_thinglist_next;
 					continue;
 				}
 
@@ -7032,7 +7032,7 @@ void T_Friction(friction_t *f)
 				thing->movefactor = f->movefactor;
 			}
 		}
-		node = node->m_snext;
+		node = node->m_thinglist_next;
 	}
 }
 
@@ -7372,7 +7372,7 @@ void T_Pusher(pusher_t *p)
 
 	// constant pushers p_wind and p_current
 	node = sec->touching_thinglist; // things touching this sector
-	for (; node; node = node->m_snext)
+	for (; node; node = node->m_thinglist_next)
 	{
 		thing = node->m_thing;
 		if (thing->flags & (MF_NOGRAVITY | MF_NOCLIP)
diff --git a/src/p_user.c b/src/p_user.c
index 4117cfc4c..c9ac9f541 100644
--- a/src/p_user.c
+++ b/src/p_user.c
@@ -1684,7 +1684,7 @@ static void P_CheckBustableBlocks(player_t *player)
 	player->mo->y += player->mo->momy;
 	P_SetThingPosition(player->mo);
 
-	for (node = player->mo->touching_sectorlist; node; node = node->m_snext)
+	for (node = player->mo->touching_sectorlist; node; node = node->m_sectorlist_next)
 	{
 		if (!node->m_sector)
 			break;
@@ -1801,7 +1801,7 @@ static void P_CheckBouncySectors(player_t *player)
 	player->mo->z += player->mo->momz;
 	P_SetThingPosition(player->mo);
 
-	for (node = player->mo->touching_sectorlist; node; node = node->m_snext)
+	for (node = player->mo->touching_sectorlist; node; node = node->m_sectorlist_next)
 	{
 		if (!node->m_sector)
 			break;
@@ -2849,86 +2849,10 @@ static boolean PIT_CheckSolidsTeeter(mobj_t *thing)
 //
 static void P_DoTeeter(player_t *player)
 {
-	msecnode_t *node;
 	boolean teeter = false;
 	boolean roverfloor; // solid 3d floors?
-	boolean checkedforteeter = false;
 	const fixed_t tiptop = FixedMul(MAXSTEPMOVE, player->mo->scale); // Distance you have to be above the ground in order to teeter.
 
-	for (node = player->mo->touching_sectorlist; node; node = node->m_snext)
-	{
-		// Ledge teetering. Check if any nearby sectors are low enough from your current one.
-		checkedforteeter = true;
-		roverfloor = false;
-		if (node->m_sector->ffloors)
-		{
-			ffloor_t *rover;
-			for (rover = node->m_sector->ffloors; rover; rover = rover->next)
-			{
-				if (!(rover->flags & FF_EXISTS)) continue;
-
-				if (P_CheckSolidLava(player->mo, rover))
-					;
-				else if (!(rover->flags & FF_BLOCKPLAYER || rover->flags & FF_QUICKSAND))
-					continue; // intangible 3d floor
-
-				if (player->mo->eflags & MFE_VERTICALFLIP)
-				{
-					if (*rover->bottomheight > node->m_sector->ceilingheight) // Above the ceiling
-						continue;
-
-					if (*rover->bottomheight > player->mo->z + player->mo->height + tiptop
-						|| (*rover->topheight < player->mo->z
-						&& player->mo->z + player->mo->height < node->m_sector->ceilingheight - tiptop))
-					{
-						teeter = true;
-						roverfloor = true;
-					}
-					else
-					{
-						teeter = false;
-						roverfloor = true;
-						break;
-					}
-				}
-				else
-				{
-					if (*rover->topheight < node->m_sector->floorheight) // Below the floor
-						continue;
-
-					if (*rover->topheight < player->mo->z - tiptop
-						|| (*rover->bottomheight > player->mo->z + player->mo->height
-						&& player->mo->z > node->m_sector->floorheight + tiptop))
-					{
-						teeter = true;
-						roverfloor = true;
-					}
-					else
-					{
-						teeter = false;
-						roverfloor = true;
-						break;
-					}
-				}
-			}
-		}
-
-		if (!teeter && !roverfloor)
-		{
-			if (player->mo->eflags & MFE_VERTICALFLIP)
-			{
-				if (node->m_sector->ceilingheight > player->mo->z + player->mo->height + tiptop)
-					teeter = true;
-			}
-			else
-			{
-				if (node->m_sector->floorheight < player->mo->z - tiptop)
-					teeter = true;
-			}
-		}
-	}
-
-	if (checkedforteeter && !teeter) // Backup code
 	{
 		subsector_t *subsec[4]; // changed abcd into array instead
 		UINT8 i;
@@ -3147,7 +3071,7 @@ teeterdone:
 		if ((player->mo->state == &states[S_PLAY_STND] || player->mo->state == &states[S_PLAY_TAP1] || player->mo->state == &states[S_PLAY_TAP2] || player->mo->state == &states[S_PLAY_SUPERSTAND]))
 			P_SetPlayerMobjState(player->mo, S_PLAY_TEETER1);
 	}
-	else if (checkedforteeter && (player->mo->state == &states[S_PLAY_TEETER1] || player->mo->state == &states[S_PLAY_TEETER2] || player->mo->state == &states[S_PLAY_SUPERTEETER]))
+	else if ((player->mo->state == &states[S_PLAY_TEETER1] || player->mo->state == &states[S_PLAY_TEETER2] || player->mo->state == &states[S_PLAY_SUPERTEETER]))
 		P_SetPlayerMobjState(player->mo, S_PLAY_STND);
 }
 
@@ -7037,7 +6961,7 @@ static void P_MovePlayer(player_t *player)
 		player->mo->y += player->mo->momy;
 		P_SetThingPosition(player->mo);
 
-		for (node = player->mo->touching_sectorlist; node; node = node->m_snext)
+		for (node = player->mo->touching_sectorlist; node; node = node->m_sectorlist_next)
 		{
 			if (!node->m_sector)
 				break;
diff --git a/src/r_defs.h b/src/r_defs.h
index 848708164..2c5860ee7 100644
--- a/src/r_defs.h
+++ b/src/r_defs.h
@@ -500,10 +500,10 @@ typedef struct subsector_s
 // Sector list node showing all sectors an object appears in.
 //
 // There are two threads that flow through these nodes. The first thread
-// starts at touching_thinglist in a sector_t and flows through the m_snext
+// starts at touching_thinglist in a sector_t and flows through the m_thinglist_next
 // links to find all mobjs that are entirely or partially in the sector.
 // The second thread starts at touching_sectorlist in an mobj_t and flows
-// through the m_tnext links to find all sectors a thing touches. This is
+// through the m_sectorlist_next links to find all sectors a thing touches. This is
 // useful when applying friction or push effects to sectors. These effects
 // can be done as thinkers that act upon all objects touching their sectors.
 // As an mobj moves through the world, these nodes are created and
@@ -515,10 +515,10 @@ typedef struct msecnode_s
 {
 	sector_t *m_sector; // a sector containing this object
 	struct mobj_s *m_thing;  // this object
-	struct msecnode_s *m_tprev;  // prev msecnode_t for this thing
-	struct msecnode_s *m_tnext;  // next msecnode_t for this thing
-	struct msecnode_s *m_sprev;  // prev msecnode_t for this sector
-	struct msecnode_s *m_snext;  // next msecnode_t for this sector
+	struct msecnode_s *m_sectorlist_prev;  // prev msecnode_t for this thing
+	struct msecnode_s *m_sectorlist_next;  // next msecnode_t for this thing
+	struct msecnode_s *m_thinglist_prev;  // prev msecnode_t for this sector
+	struct msecnode_s *m_thinglist_next;  // next msecnode_t for this sector
 	boolean visited; // used in search algorithms
 } msecnode_t;
 
@@ -526,10 +526,10 @@ typedef struct mprecipsecnode_s
 {
 	sector_t *m_sector; // a sector containing this object
 	struct precipmobj_s *m_thing;  // this object
-	struct mprecipsecnode_s *m_tprev;  // prev msecnode_t for this thing
-	struct mprecipsecnode_s *m_tnext;  // next msecnode_t for this thing
-	struct mprecipsecnode_s *m_sprev;  // prev msecnode_t for this sector
-	struct mprecipsecnode_s *m_snext;  // next msecnode_t for this sector
+	struct mprecipsecnode_s *m_sectorlist_prev;  // prev msecnode_t for this thing
+	struct mprecipsecnode_s *m_sectorlist_next;  // next msecnode_t for this thing
+	struct mprecipsecnode_s *m_thinglist_prev;  // prev msecnode_t for this sector
+	struct mprecipsecnode_s *m_thinglist_next;  // next msecnode_t for this sector
 	boolean visited; // used in search algorithms
 } mprecipsecnode_t;
 
diff --git a/src/r_segs.c b/src/r_segs.c
index ec3eaa180..59b4f5db9 100644
--- a/src/r_segs.c
+++ b/src/r_segs.c
@@ -1883,12 +1883,13 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 		// a single sided line is terminal, so it must mark ends
 		markfloor = markceiling = true;
 #ifdef ESLOPE
-		if (!(linedef->flags & ML_EFFECT1)) {
+		if (linedef->flags & ML_EFFECT2) {
 			if (linedef->flags & ML_DONTPEGBOTTOM)
 				rw_midtexturemid = frontsector->floorheight + textureheight[sidedef->midtexture] - viewz;
 			else
-				rw_midtexturemid = frontsector->ceilingheight;
+				rw_midtexturemid = frontsector->ceilingheight - viewz;
 		}
+		else
 #endif
 		if (linedef->flags & ML_DONTPEGBOTTOM)
 		{
@@ -2507,6 +2508,15 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 #ifdef ESLOPE
 			maskedtextureheight = ds_p->maskedtextureheight; // note to red, this == &(ds_p->maskedtextureheight[0])
 
+#ifdef POLYOBJECTS
+			if (curline->polyseg) { // use REAL front and back floors please, so midtexture rendering isn't mucked up
+				rw_midtextureslide = rw_midtexturebackslide = 0;
+				if (!!(linedef->flags & ML_DONTPEGBOTTOM) ^ !!(linedef->flags & ML_EFFECT3))
+					rw_midtexturemid = rw_midtextureback = max(curline->frontsector->floorheight, curline->backsector->floorheight) - viewz;
+				else
+					rw_midtexturemid = rw_midtextureback = min(curline->frontsector->ceilingheight, curline->backsector->ceilingheight) - viewz;
+			} else
+#endif
 			// Set midtexture starting height
 			if (linedef->flags & ML_EFFECT2) { // Ignore slopes when texturing
 				rw_midtextureslide = rw_midtexturebackslide = 0;