diff --git a/src/p_switch.cpp b/src/p_switch.cpp
index 25a878884..9865b65c1 100644
--- a/src/p_switch.cpp
+++ b/src/p_switch.cpp
@@ -490,11 +490,25 @@ bool P_CheckSwitchRange(AActor *user, line_t *line, int sideno)
 	dlu.dy = finesine[user->angle >> ANGLETOFINESHIFT];
 	inter = P_InterceptVector(&dll, &dlu);
 
-	checkx = dll.x + FixedMul(dll.dx, inter);
-	checky = dll.y + FixedMul(dll.dy, inter);
 
-	// one sided line
-	if (line->sidedef[1] == NULL) 
+	// Polyobjects must test the containing sector, not the one they originate from.
+	if (line->sidedef[0]->Flags & WALLF_POLYOBJ)
+	{
+		// Get a check point slightly inside the polyobject so that this still works
+		// if the polyobject lies directly on a sector boundary
+		checkx = dll.x + FixedMul(dll.dx, inter + (FRACUNIT/100));
+		checky = dll.y + FixedMul(dll.dy, inter + (FRACUNIT/100));
+		front = P_PointInSector(checkx, checky);
+	}
+	else
+	{
+		checkx = dll.x + FixedMul(dll.dx, inter);
+		checky = dll.y + FixedMul(dll.dy, inter);
+	}
+
+
+	// one sided line or polyobject
+	if (line->sidedef[1] == NULL || (line->sidedef[0]->Flags & WALLF_POLYOBJ))
 	{
 	onesided:
 		fixed_t sectorc = front->ceilingplane.ZatPoint(checkx, checky);
diff --git a/src/po_man.cpp b/src/po_man.cpp
index 828ea951a..37faf119a 100644
--- a/src/po_man.cpp
+++ b/src/po_man.cpp
@@ -1545,6 +1545,7 @@ static void TranslateToStartSpot (int tag, int originX, int originY)
 	validcount++;
 	for (i = 0; i < po->numsegs; i++, tempSeg++, tempPt++)
 	{
+		(*tempSeg)->sidedef->Flags |= WALLF_POLYOBJ;
 		if ((*tempSeg)->linedef->validcount != validcount)
 		{
 			(*tempSeg)->linedef->bbox[BOXTOP] -= deltaY;
@@ -1581,14 +1582,6 @@ static void TranslateToStartSpot (int tag, int originX, int originY)
 		I_Error ("PO_TranslateToStartSpot: Multiple polyobjs in a single subsector.\n");
 	}
 	sub->poly = po;
-	// Reassign the sides of the polyobj to its new sector.
-	sector_t *sec = P_PointInSector (avg.x << FRACBITS, avg.y << FRACBITS);
-	for (i = 0; i < po->numsegs; ++i)
-	{
-		po->segs[i]->linedef->frontsector = sec;
-		po->segs[i]->linedef->sidedef[0]->sector = sec;
-		po->segs[i]->frontsector = sec;
-	}
 }
 
 //==========================================================================
diff --git a/src/r_defs.h b/src/r_defs.h
index 7d02fb4eb..a14a819ce 100644
--- a/src/r_defs.h
+++ b/src/r_defs.h
@@ -725,6 +725,7 @@ enum
 	WALLF_SMOOTHLIGHTING = 8,   // Similar to autocontrast but applies to all angles.
 	WALLF_CLIP_MIDTEX	 = 16,	// Like the line counterpart, but only for this side.
 	WALLF_WRAP_MIDTEX	 = 32,	// Like the line counterpart, but only for this side.
+	WALLF_POLYOBJ		 = 64,	// This wall belongs to a polyobject.
 };
 
 struct side_t