diff --git a/src/m_bbox.h b/src/m_bbox.h
index febf9d2a25..256393d600 100644
--- a/src/m_bbox.h
+++ b/src/m_bbox.h
@@ -57,6 +57,15 @@ public:
 		m_Box[BOXBOTTOM] = m_Box[BOXLEFT] = FIXED_MAX;
 	}
 
+	// Returns a bounding box that encloses both bounding boxes
+	FBoundingBox operator | (const FBoundingBox &box2) const
+	{
+		return FBoundingBox(m_Box[BOXLEFT] < box2.m_Box[BOXLEFT] ? m_Box[BOXLEFT] : box2.m_Box[BOXLEFT],
+							m_Box[BOXBOTTOM] < box2.m_Box[BOXBOTTOM] ? m_Box[BOXBOTTOM] : box2.m_Box[BOXBOTTOM],
+							m_Box[BOXRIGHT] > box2.m_Box[BOXRIGHT] ? m_Box[BOXRIGHT] : box2.m_Box[BOXRIGHT],
+							m_Box[BOXTOP] > box2.m_Box[BOXTOP] ? m_Box[BOXTOP] : box2.m_Box[BOXTOP]);
+	}
+
 	void AddToBox (fixed_t x, fixed_t y);
 
 	inline fixed_t Top () const { return m_Box[BOXTOP]; }
diff --git a/src/po_man.cpp b/src/po_man.cpp
index 3355b6ca1e..1464f3ee5d 100644
--- a/src/po_man.cpp
+++ b/src/po_man.cpp
@@ -986,6 +986,7 @@ void FPolyObj::CalcCenter()
 
 bool FPolyObj::MovePolyobj (int x, int y, bool force)
 {
+	FBoundingBox oldbounds = Bounds;
 	UnLinkPolyobj ();
 	DoMovePolyobj (x, y);
 
@@ -1013,6 +1014,7 @@ bool FPolyObj::MovePolyobj (int x, int y, bool force)
 	CenterSpot.y += y;
 	LinkPolyobj ();
 	ClearSubsectorLinks();
+	RecalcActorFloorCeil(Bounds | oldbounds);
 	return true;
 }
 
@@ -1065,6 +1067,7 @@ bool FPolyObj::RotatePolyobj (angle_t angle)
 {
 	int an;
 	bool blocked;
+	FBoundingBox oldbounds = Bounds;
 
 	an = (this->angle+angle)>>ANGLETOFINESHIFT;
 
@@ -1103,6 +1106,7 @@ bool FPolyObj::RotatePolyobj (angle_t angle)
 	this->angle += angle;
 	LinkPolyobj();
 	ClearSubsectorLinks();
+	RecalcActorFloorCeil(Bounds | oldbounds);
 	return true;
 }
 
@@ -1338,6 +1342,26 @@ void FPolyObj::LinkPolyobj ()
 	}
 }
 
+//===========================================================================
+//
+// FPolyObj :: RecalcActorFloorCeil
+//
+// For each actor within the bounding box, recalculate its floorz, ceilingz,
+// and related values.
+//
+//===========================================================================
+
+void FPolyObj::RecalcActorFloorCeil(FBoundingBox bounds) const
+{
+	FBlockThingsIterator it(bounds);
+	AActor *actor;
+
+	while ((actor = it.Next()) != NULL)
+	{
+		P_FindFloorCeiling(actor);
+	}
+}
+
 //===========================================================================
 //
 // PO_ClosestPoint
diff --git a/src/po_man.h b/src/po_man.h
index 5603095d56..35dc2af9ce 100644
--- a/src/po_man.h
+++ b/src/po_man.h
@@ -76,6 +76,7 @@ struct FPolyObj
 	bool RotatePolyobj (angle_t angle);
 	void ClosestPoint(fixed_t fx, fixed_t fy, fixed_t &ox, fixed_t &oy, side_t **side) const;
 	void LinkPolyobj ();
+	void RecalcActorFloorCeil(FBoundingBox bounds) const;
 	void CreateSubsectorLinks();
 	void ClearSubsectorLinks();
 	void CalcCenter();