diff --git a/src/p_map.c b/src/p_map.c
index a9ec296b8..6beca92f1 100644
--- a/src/p_map.c
+++ b/src/p_map.c
@@ -1808,7 +1808,7 @@ static boolean PIT_CheckLine(line_t *ld)
 	{
 		tmceilingz = opentop;
 		ceilingline = ld;
-		tmceilingrover = NULL;
+		tmceilingrover = openceilingrover;
 #ifdef ESLOPE
 		tmceilingslope = opentopslope;
 #endif
@@ -1817,7 +1817,7 @@ static boolean PIT_CheckLine(line_t *ld)
 	if (openbottom > tmfloorz)
 	{
 		tmfloorz = openbottom;
-		tmfloorrover = NULL;
+		tmfloorrover = openfloorrover;
 #ifdef ESLOPE
 		tmfloorslope = openbottomslope;
 #endif
@@ -2089,6 +2089,7 @@ boolean P_CheckPosition(mobj_t *thing, fixed_t x, fixed_t y)
 #ifdef ESLOPE
 							tmfloorslope = NULL;
 #endif
+							tmfloorrover = NULL;
 						}
 
 						if (polybottom < tmceilingz && abs(delta1) >= abs(delta2)) {
@@ -2096,6 +2097,7 @@ boolean P_CheckPosition(mobj_t *thing, fixed_t x, fixed_t y)
 #ifdef ESLOPE
 							tmceilingslope = NULL;
 #endif
+							tmceilingrover = NULL;
 						}
 					}
 					plink = (polymaplink_t *)(plink->link.next);
@@ -4085,6 +4087,7 @@ static boolean PIT_ChangeSector(mobj_t *thing, boolean realcrush)
 boolean P_CheckSector(sector_t *sector, boolean crunch)
 {
 	msecnode_t *n;
+	size_t i;
 
 	nofit = false;
 	crushchange = crunch;
@@ -4099,9 +4102,57 @@ boolean P_CheckSector(sector_t *sector, boolean crunch)
 
 
 	// First, let's see if anything will keep it from crushing.
+
+	// Sal: This stupid function chain is required to fix polyobjects not being able to crush.
+	// Monster Iestyn: don't use P_CheckSector actually just look for objects in the blockmap instead
+	validcount++;
+
+	for (i = 0; i < sector->linecount; i++)
+	{
+		if (sector->lines[i]->polyobj)
+		{
+			polyobj_t *po = sector->lines[i]->polyobj;
+			if (po->validcount == validcount)
+				continue; // skip if already checked
+			if (!(po->flags & POF_SOLID))
+				continue;
+			if (po->lines[0]->backsector == sector) // Make sure you're currently checking the control sector
+			{
+				INT32 x, y;
+				po->validcount = validcount;
+
+				for (y = po->blockbox[BOXBOTTOM]; y <= po->blockbox[BOXTOP]; ++y)
+				{
+					for (x = po->blockbox[BOXLEFT]; x <= po->blockbox[BOXRIGHT]; ++x)
+					{
+						mobj_t *mo;
+
+						if (x < 0 || y < 0 || x >= bmapwidth || y >= bmapheight)
+							continue;
+
+						mo = blocklinks[y * bmapwidth + x];
+
+						for (; mo; mo = mo->bnext)
+						{
+							// Monster Iestyn: do we need to check if a mobj has already been checked? ...probably not I suspect
+
+							if (!P_MobjTouchingPolyobj(po, mo))
+								continue;
+
+							if (!PIT_ChangeSector(mo, false))
+							{
+								nofit = true;
+								return nofit;
+							}
+						}
+					}
+				}
+			}
+		}
+	}
+
 	if (sector->numattached)
 	{
-		size_t i;
 		sector_t *sec;
 		for (i = 0; i < sector->numattached; i++)
 		{
@@ -4161,9 +4212,53 @@ boolean P_CheckSector(sector_t *sector, boolean crunch)
 	} while (n); // repeat from scratch until all things left are marked valid
 
 	// Nothing blocked us, so lets crush for real!
+
+	// Sal: This stupid function chain is required to fix polyobjects not being able to crush.
+	// Monster Iestyn: don't use P_CheckSector actually just look for objects in the blockmap instead
+	validcount++;
+
+	for (i = 0; i < sector->linecount; i++)
+	{
+		if (sector->lines[i]->polyobj)
+		{
+			polyobj_t *po = sector->lines[i]->polyobj;
+			if (po->validcount == validcount)
+				continue; // skip if already checked
+			if (!(po->flags & POF_SOLID))
+				continue;
+			if (po->lines[0]->backsector == sector) // Make sure you're currently checking the control sector
+			{
+				INT32 x, y;
+				po->validcount = validcount;
+
+				for (y = po->blockbox[BOXBOTTOM]; y <= po->blockbox[BOXTOP]; ++y)
+				{
+					for (x = po->blockbox[BOXLEFT]; x <= po->blockbox[BOXRIGHT]; ++x)
+					{
+						mobj_t *mo;
+
+						if (x < 0 || y < 0 || x >= bmapwidth || y >= bmapheight)
+							continue;
+
+						mo = blocklinks[y * bmapwidth + x];
+
+						for (; mo; mo = mo->bnext)
+						{
+							// Monster Iestyn: do we need to check if a mobj has already been checked? ...probably not I suspect
+
+							if (!P_MobjTouchingPolyobj(po, mo))
+								continue;
+
+							PIT_ChangeSector(mo, true);
+							return nofit;
+						}
+					}
+				}
+			}
+		}
+	}
 	if (sector->numattached)
 	{
-		size_t i;
 		sector_t *sec;
 		for (i = 0; i < sector->numattached; i++)
 		{
diff --git a/src/p_maputl.c b/src/p_maputl.c
index 0ca84096a..740797fb0 100644
--- a/src/p_maputl.c
+++ b/src/p_maputl.c
@@ -311,6 +311,7 @@ fixed_t opentop, openbottom, openrange, lowfloor, highceiling;
 #ifdef ESLOPE
 pslope_t *opentopslope, *openbottomslope;
 #endif
+ffloor_t *openfloorrover, *openceilingrover;
 
 // P_CameraLineOpening
 // P_LineOpening, but for camera
@@ -517,6 +518,8 @@ void P_LineOpening(line_t *linedef, mobj_t *mobj)
 	I_Assert(front != NULL);
 	I_Assert(back != NULL);
 
+	openfloorrover = openceilingrover = NULL;
+
 	{ // Set open and high/low values here
 		fixed_t frontheight, backheight;
 
@@ -641,6 +644,8 @@ void P_LineOpening(line_t *linedef, mobj_t *mobj)
 			pslope_t *ceilingslope = opentopslope;
 			pslope_t *floorslope = openbottomslope;
 #endif
+			ffloor_t *floorrover = NULL;
+			ffloor_t *ceilingrover = NULL;
 
 			// Check for frontsector's fake floors
 			for (rover = front->ffloors; rover; rover = rover->next)
@@ -668,6 +673,7 @@ void P_LineOpening(line_t *linedef, mobj_t *mobj)
 #ifdef ESLOPE
 						ceilingslope = *rover->b_slope;
 #endif
+						ceilingrover = rover;
 					}
 					else if (bottomheight < highestceiling)
 						highestceiling = bottomheight;
@@ -680,6 +686,7 @@ void P_LineOpening(line_t *linedef, mobj_t *mobj)
 #ifdef ESLOPE
 						floorslope = *rover->t_slope;
 #endif
+						floorrover = rover;
 					}
 					else if (topheight > lowestfloor)
 						lowestfloor = topheight;
@@ -712,6 +719,7 @@ void P_LineOpening(line_t *linedef, mobj_t *mobj)
 #ifdef ESLOPE
 						ceilingslope = *rover->b_slope;
 #endif
+						ceilingrover = rover;
 					}
 					else if (bottomheight < highestceiling)
 						highestceiling = bottomheight;
@@ -724,6 +732,7 @@ void P_LineOpening(line_t *linedef, mobj_t *mobj)
 #ifdef ESLOPE
 						floorslope = *rover->t_slope;
 #endif
+						floorrover = rover;
 					}
 					else if (topheight > lowestfloor)
 						lowestfloor = topheight;
@@ -743,6 +752,7 @@ void P_LineOpening(line_t *linedef, mobj_t *mobj)
 #ifdef ESLOPE
 					ceilingslope = NULL;
 #endif
+					ceilingrover = NULL;
 				}
 				else if (polysec->floorheight < highestceiling && delta1 >= delta2)
 					highestceiling = polysec->floorheight;
@@ -752,6 +762,7 @@ void P_LineOpening(line_t *linedef, mobj_t *mobj)
 #ifdef ESLOPE
 					floorslope = NULL;
 #endif
+					floorrover = NULL;
 				}
 				else if (polysec->ceilingheight > lowestfloor && delta1 < delta2)
 					lowestfloor = polysec->ceilingheight;
@@ -765,6 +776,7 @@ void P_LineOpening(line_t *linedef, mobj_t *mobj)
 #ifdef ESLOPE
 				openbottomslope = floorslope;
 #endif
+				openfloorrover = floorrover;
 			}
 
 			if (lowestceiling < opentop) {
@@ -772,6 +784,7 @@ void P_LineOpening(line_t *linedef, mobj_t *mobj)
 #ifdef ESLOPE
 				opentopslope = ceilingslope;
 #endif
+				openceilingrover = ceilingrover;
 			}
 
 			if (lowestfloor > lowfloor)
diff --git a/src/p_maputl.h b/src/p_maputl.h
index 1fcb68d4c..5042817c5 100644
--- a/src/p_maputl.h
+++ b/src/p_maputl.h
@@ -58,6 +58,7 @@ extern fixed_t opentop, openbottom, openrange, lowfloor, highceiling;
 #ifdef ESLOPE
 extern pslope_t *opentopslope, *openbottomslope;
 #endif
+extern ffloor_t *openfloorrover, *openceilingrover;
 
 void P_LineOpening(line_t *plinedef, mobj_t *mobj);
 
diff --git a/src/p_polyobj.c b/src/p_polyobj.c
index 475fa41b7..040bdca2a 100644
--- a/src/p_polyobj.c
+++ b/src/p_polyobj.c
@@ -1873,7 +1873,8 @@ void T_PolyObjWaypoint(polywaypoint_t *th)
 		po->lines[0]->backsector->floorheight = target->z - amtz;
 		po->lines[0]->backsector->ceilingheight = target->z + amtz;
 		// Sal: Remember to check your sectors!
-		P_CheckSector(po->lines[0]->frontsector, (boolean)(po->damage));
+		// Monster Iestyn: we only need to bother with the back sector, now that P_CheckSector automatically checks the blockmap
+		//  updating objects in the front one too just added teleporting to ground bugs
 		P_CheckSector(po->lines[0]->backsector, (boolean)(po->damage));
 		// Apply action to mirroring polyobjects as well
 		start = 0;
@@ -1887,7 +1888,8 @@ void T_PolyObjWaypoint(polywaypoint_t *th)
 			po->lines[0]->backsector->floorheight += diffz; // move up/down by same amount as the parent did
 			po->lines[0]->backsector->ceilingheight += diffz;
 			// Sal: Remember to check your sectors!
-			P_CheckSector(po->lines[0]->frontsector, (boolean)(po->damage));
+			// Monster Iestyn: we only need to bother with the back sector, now that P_CheckSector automatically checks the blockmap
+			//  updating objects in the front one too just added teleporting to ground bugs
 			P_CheckSector(po->lines[0]->backsector, (boolean)(po->damage));
 		}
 
@@ -2050,8 +2052,9 @@ void T_PolyObjWaypoint(polywaypoint_t *th)
 	po->lines[0]->backsector->floorheight += momz;
 	po->lines[0]->backsector->ceilingheight += momz;
 	// Sal: Remember to check your sectors!
-	P_CheckSector(po->lines[0]->frontsector, (boolean)(po->damage)); // frontsector is NEEDED for crushing
-	P_CheckSector(po->lines[0]->backsector, (boolean)(po->damage)); // backsector may not be necessary, but just in case
+	// Monster Iestyn: we only need to bother with the back sector, now that P_CheckSector automatically checks the blockmap
+	//  updating objects in the front one too just added teleporting to ground bugs
+	P_CheckSector(po->lines[0]->backsector, (boolean)(po->damage));
 
 	// Apply action to mirroring polyobjects as well
 	start = 0;
@@ -2065,7 +2068,8 @@ void T_PolyObjWaypoint(polywaypoint_t *th)
 		po->lines[0]->backsector->floorheight += momz;
 		po->lines[0]->backsector->ceilingheight += momz;
 		// Sal: Remember to check your sectors!
-		P_CheckSector(po->lines[0]->frontsector, (boolean)(po->damage));
+		// Monster Iestyn: we only need to bother with the back sector, now that P_CheckSector automatically checks the blockmap
+		//  updating objects in the front one too just added teleporting to ground bugs
 		P_CheckSector(po->lines[0]->backsector, (boolean)(po->damage));
 	}
 }