diff --git a/src/hardware/hw_main.c b/src/hardware/hw_main.c
index 0db3e9034..47ea88ce8 100644
--- a/src/hardware/hw_main.c
+++ b/src/hardware/hw_main.c
@@ -2857,9 +2857,10 @@ static void HWR_Subsector(size_t num)
 #ifdef DOPLANES
 	// -------------------- WATER IN DEV. TEST ------------------------
 	//dck hack : use abs(tag) for waterheight
-	if (gr_frontsector->tag < 0)
+	//ilag : Since we changed to UINT16 for sector tags, simulate INT16
+	if (gr_frontsector->tag > 32767)
 	{
-		wh = ((-gr_frontsector->tag) <<FRACBITS) + (FRACUNIT/2);
+		wh = ((65535-gr_frontsector->tag) <<FRACBITS) + (FRACUNIT/2);
 		if (wh > gr_frontsector->floorheight &&
 			wh < gr_frontsector->ceilingheight)
 		{
diff --git a/src/p_mobj.c b/src/p_mobj.c
index 81ad1a5ee..29ba5d043 100644
--- a/src/p_mobj.c
+++ b/src/p_mobj.c
@@ -3670,7 +3670,7 @@ static void P_Boss3Thinker(mobj_t *mobj)
 // Move Boss4's sectors by delta.
 static boolean P_Boss4MoveCage(fixed_t delta)
 {
-	const INT16 tag = -2;
+	const UINT16 tag = 65534;
 	INT32 snum;
 	sector_t *sector;
 	for (snum = sectors[tag%numsectors].firsttag; snum != -1; snum = sector->nexttag)
@@ -3719,7 +3719,7 @@ static void P_Boss4PinchSpikeballs(mobj_t *mobj, angle_t angle, fixed_t fz)
 // Destroy cage FOFs.
 static void P_Boss4DestroyCage(void)
 {
-	const INT16 tag = -2;
+	const UINT16 tag = 65534;
 	INT32 snum, next;
 	size_t a;
 	sector_t *sector, *rsec;
diff --git a/src/r_defs.h b/src/r_defs.h
index dd096c3eb..f818ed65c 100644
--- a/src/r_defs.h
+++ b/src/r_defs.h
@@ -242,7 +242,7 @@ typedef struct sector_s
 	INT32 ceilingpic;
 	INT16 lightlevel;
 	INT16 special;
-	INT16 tag;
+	UINT16 tag;
 	INT32 nexttag, firsttag; // for fast tag searches
 
 	// origin for any sounds played by the sector