diff --git a/src/p_mobj.c b/src/p_mobj.c
index 6a3ac9ee..b9412ee7 100644
--- a/src/p_mobj.c
+++ b/src/p_mobj.c
@@ -4436,7 +4436,7 @@ static void P_Boss4MoveSpikeballs(mobj_t *mobj, angle_t angle, fixed_t fz)
 {
 	INT32 s;
 	mobj_t *base = mobj, *seg;
-	fixed_t dist, bz = (mobj->spawnpoint->z+16)<<FRACBITS;
+	fixed_t dist, bz = mobj->watertop+(16<<FRACBITS);
 	while ((base = base->tracer))
 	{
 		for (seg = base, dist = 172*FRACUNIT, s = 9; seg; seg = seg->hnext, dist += 124*FRACUNIT, --s)
@@ -4450,7 +4450,7 @@ static void P_Boss4PinchSpikeballs(mobj_t *mobj, angle_t angle, fixed_t fz)
 {
 	INT32 s;
 	mobj_t *base = mobj, *seg;
-	fixed_t dist, bz = (mobj->spawnpoint->z+16)<<FRACBITS;
+	fixed_t dist, bz = mobj->watertop+(16<<FRACBITS);
 	while ((base = base->tracer))
 	{
 		for (seg = base, dist = 112*FRACUNIT, s = 9; seg; seg = seg->hnext, dist += 132*FRACUNIT, --s)
@@ -4566,7 +4566,7 @@ static void P_Boss4Thinker(mobj_t *mobj)
 			INT32 i, arm;
 			mobj_t *seg, *base = mobj;
 			// First frame init, spawn all the things.
-			mobj->spawnpoint->z = mobj->z>>FRACBITS;
+			mobj->watertop = mobj->z;
 			z = mobj->z + mobj->height/2 - mobjinfo[MT_EGGMOBILE4_MACE].height/2;
 			for (arm = 0; arm <3 ; arm++)
 			{
@@ -4622,7 +4622,7 @@ static void P_Boss4Thinker(mobj_t *mobj)
 	case 3:
 	{
 		fixed_t z;
-		if (mobj->z < (mobj->spawnpoint->z+512)<<FRACBITS)
+		if (mobj->z < mobj->watertop+(512<<FRACBITS))
 			mobj->momz = 8*FRACUNIT;
 		else
 		{
@@ -4631,7 +4631,7 @@ static void P_Boss4Thinker(mobj_t *mobj)
 		}
 		mobj->movecount += 400<<(FRACBITS>>1);
 		mobj->movecount %= 360*FRACUNIT;
-		z = mobj->z - (mobj->spawnpoint->z<<FRACBITS) - mobjinfo[MT_EGGMOBILE4_MACE].height - mobj->height/2;
+		z = mobj->z - mobj->watertop - mobjinfo[MT_EGGMOBILE4_MACE].height - mobj->height/2;
 		if (z < 0) // We haven't risen high enough to pull the spikeballs along yet
 			P_Boss4MoveSpikeballs(mobj, FixedAngle(mobj->movecount), 0); // So don't pull the spikeballs along yet.
 		else
@@ -4641,13 +4641,13 @@ static void P_Boss4Thinker(mobj_t *mobj)
 	// Pinch phase!
 	case 4:
 	{
-		if (mobj->z < (mobj->spawnpoint->z+512+128*(mobj->info->damage-mobj->health))<<FRACBITS)
+		if (mobj->z < (mobj->watertop + ((512+128*(mobj->info->damage-mobj->health))<<FRACBITS)))
 			mobj->momz = 8*FRACUNIT;
 		else
 			mobj->momz = 0;
 		mobj->movecount += (800+800*(mobj->info->damage-mobj->health))<<(FRACBITS>>1);
 		mobj->movecount %= 360*FRACUNIT;
-		P_Boss4PinchSpikeballs(mobj, FixedAngle(mobj->movecount), mobj->z - (mobj->spawnpoint->z<<FRACBITS) - mobjinfo[MT_EGGMOBILE4_MACE].height - mobj->height/2);
+		P_Boss4PinchSpikeballs(mobj, FixedAngle(mobj->movecount), mobj->z - mobj->watertop - mobjinfo[MT_EGGMOBILE4_MACE].height - mobj->height/2);
 
 		if (!mobj->target || !mobj->target->health)
 			P_SupermanLook4Players(mobj);