diff --git a/src/p_local.h b/src/p_local.h
index ac92ad7b70..48014f993e 100644
--- a/src/p_local.h
+++ b/src/p_local.h
@@ -354,7 +354,6 @@ msecnode_t*	P_DelSecnode(msecnode_t *, msecnode_t *sector_t::*head);
 void	P_CreateSecNodeList(AActor*);		// phares 3/14/98
 double	P_GetMoveFactor(const AActor *mo, double *frictionp);	// phares  3/6/98
 double		P_GetFriction(const AActor *mo, double *frictionfactor);
-bool	Check_Sides(AActor *, int, int);					// phares
 
 // [RH] 
 const secplane_t * P_CheckSlopeWalk(AActor *actor, DVector2 &move);
diff --git a/src/p_map.cpp b/src/p_map.cpp
index 5623af25a9..e0ee1eaec7 100644
--- a/src/p_map.cpp
+++ b/src/p_map.cpp
@@ -2533,13 +2533,13 @@ bool P_CheckMove(AActor *thing, const DVector2 &pos, int flags)
 					return false;
 				}
 			}
-			else if (flags & PCM_DROPOFF)
+			else if ((flags & PCM_DROPOFF) && !(thing->flags & (MF_FLOAT|MF_DROPOFF)))
 			{
 				const DVector3 oldpos = thing->Pos();
 				thing->SetOrigin(pos.X, pos.Y, newz, true);
-				bool hcheck = (newz - thing->MaxDropOffHeight > thing->dropoffz);
+				bool hcheck = (newz - thing->dropoffz > thing->MaxDropOffHeight);
 				thing->SetOrigin(oldpos, true);
-				if (hcheck && !(thing->flags & MF_FLOAT) && !(i_compatflags & COMPATF_DROPOFF))
+				if (hcheck)
 				{
 					return false;
 				}
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index ecd6b8d1c6..419da0ccb3 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -4390,6 +4390,7 @@ void AActor::Deactivate (AActor *activator)
 void AActor::Destroy ()
 {
 	ClearRenderSectorList();
+	ClearRenderLineList();
 
 	// [RH] Destroy any inventory this actor is carrying
 	DestroyAllInventory ();
diff --git a/src/p_sectors.cpp b/src/p_sectors.cpp
index 9199f08128..ed80875434 100644
--- a/src/p_sectors.cpp
+++ b/src/p_sectors.cpp
@@ -1126,11 +1126,9 @@ bool P_AlignFlat (int linenum, int side, int fc)
 	if (!sec)
 		return false;
 
-	DVector2 pos = line->v1->fPos();
-	DVector2 pos2 = line->v2->fPos();
-	DAngle angle = (pos2 - pos).Angle();
+	DAngle angle = line->Delta().Angle();
 	DAngle norm = angle - 90;
-	double dist = norm.Cos() * pos.X + norm.Sin() * pos.Y;
+	double dist = -(norm.Cos() * line->v1->fX() + norm.Sin() * line->v1->fY());
 
 	if (side)
 	{
diff --git a/src/s_sound.cpp b/src/s_sound.cpp
index d888c9ec25..1a9210c2a2 100644
--- a/src/s_sound.cpp
+++ b/src/s_sound.cpp
@@ -1396,8 +1396,6 @@ static void S_LoadSound3D(sfxinfo_t *sfx)
     if(sfx->data3d.isValid())
         return;
 
-    unsigned int i;
-
     DPrintf("Loading monoized sound \"%s\" (%td)\n", sfx->name.GetChars(), sfx - &S_sfx[0]);
 
     int size = Wads.LumpLength(sfx->lumpnum);