diff --git a/Graphics/levels/Chapter04/Level01/Level01.MEX b/Graphics/levels/Chapter04/Level01/Level01.MEX
index 0a99b2f45..192120926 100644
Binary files a/Graphics/levels/Chapter04/Level01/Level01.MEX and b/Graphics/levels/Chapter04/Level01/Level01.MEX differ
diff --git a/Graphics/levels/Chapter04/Level01/level01.Mep b/Graphics/levels/Chapter04/Level01/level01.Mep
index f7e4cf87f..c92e28322 100644
Binary files a/Graphics/levels/Chapter04/Level01/level01.Mep and b/Graphics/levels/Chapter04/Level01/level01.Mep differ
diff --git a/source/enemy/nanemone.cpp b/source/enemy/nanemone.cpp
index 019b30cc2..507b36667 100644
--- a/source/enemy/nanemone.cpp
+++ b/source/enemy/nanemone.cpp
@@ -62,9 +62,9 @@ void CNpcAnemoneEnemy::postInit()
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void CNpcAnemoneEnemy::setHeading( s32 xPos, s32 yPos )
+void CNpcAnemoneEnemy::setHeading( s32 xPos, s32 yPos, s32 xOrig, s32 yOrig )
 {
-	m_heading = ( ratan2( ( ( yPos << 4 ) + 16 ) - Pos.vy, ( ( xPos << 4 ) + 8 ) - Pos.vx ) ) & 4095;
+	m_heading = ( ratan2( yPos - yOrig, xPos - xOrig ) ) & 4095;
 
 	int newHeading = ( m_heading - 1024 ) & 4095;
 
@@ -121,7 +121,7 @@ void CNpcAnemone1Enemy::processClose( int _frames )
 	s16 maxTurnRate = m_data[m_type].turnSpeed;
 	bool withinRange = false;
 
-	s16 headingToPlayer = ratan2( playerYDist, playerXDist );
+	s16 headingToPlayer = ratan2( playerYDist, playerXDist ) & 4095;
 
 	decDir = m_fireHeading - headingToPlayer;
 
diff --git a/source/enemy/nanemone.h b/source/enemy/nanemone.h
index cba01897a..6cf04532e 100644
--- a/source/enemy/nanemone.h
+++ b/source/enemy/nanemone.h
@@ -22,7 +22,7 @@ class	CNpcAnemoneEnemy : public CNpcEnemy
 {
 public:
 	virtual void		postInit();
-	void				setHeading( s32 xPos, s32 yPos );
+	void				setHeading( s32 xPos, s32 yPos, s32 xOrig, s32 yOrig );
 protected:
 	void				processEnemyCollision( CThing *thisThing );
 	bool				processSensor();
diff --git a/source/enemy/nclam.cpp b/source/enemy/nclam.cpp
index ec05de4f7..ae05f67be 100644
--- a/source/enemy/nclam.cpp
+++ b/source/enemy/nclam.cpp
@@ -130,7 +130,7 @@ void CNpcJumpingClamEnemy::setupWaypoints( sThingActor *ThisActor )
 		endXPos = newXPos;
 		endYPos = newYPos;
 
-		setHeading( newXPos, newYPos );
+		setHeading( newXPos, newYPos, startXPos, startYPos );
 
 		s32 xDist = ( endXPos - startXPos ) << 4;
 		s32 yDist = ( endYPos - startYPos ) << 4;
diff --git a/source/enemy/ndustdev.cpp b/source/enemy/ndustdev.cpp
index 747881f89..b712c1ad2 100644
--- a/source/enemy/ndustdev.cpp
+++ b/source/enemy/ndustdev.cpp
@@ -196,7 +196,7 @@ void CNpcDustDevilEnemy::processMovementModifier( int _frames, s32 distX, s32 di
 	s32 xDist = testPos2.vx - testPos1.vx;
 	s32 yDist = testPos2.vy - testPos1.vy;
 
-	s16 heading = ratan2( yDist, xDist );
+	s16 heading = ratan2( yDist, xDist ) & 4095;
 
 	m_drawRotation = heading;
 }
diff --git a/source/enemy/ngeneric.cpp b/source/enemy/ngeneric.cpp
index daa9039f0..d578e1d09 100644
--- a/source/enemy/ngeneric.cpp
+++ b/source/enemy/ngeneric.cpp
@@ -28,7 +28,7 @@ void CNpcEnemy::processGenericGotoTarget( int _frames, s32 xDist, s32 yDist, s32
 {
 	s16 decDir, incDir, moveDist;
 	s32 moveX, moveY;
-	s16 headingToTarget = ratan2( yDist, xDist );
+	s16 headingToTarget = ratan2( yDist, xDist ) & 4095;
 	s16 maxTurnRate = m_data[m_type].turnSpeed;
 
 	decDir = m_heading - headingToTarget;
@@ -166,7 +166,7 @@ bool CNpcEnemy::processGroundCollisionReverse( s32 *moveX, s32 *moveY )
 
 			*moveX = -(*moveX);
 
-			m_heading = ratan2( *moveY, *moveX );
+			m_heading = ratan2( *moveY, *moveX ) & 4095;
 		}
 		else if ( !xBlocked && yBlocked )
 		{
@@ -174,7 +174,7 @@ bool CNpcEnemy::processGroundCollisionReverse( s32 *moveX, s32 *moveY )
 
 			*moveY = -(*moveY);
 
-			m_heading = ratan2( *moveY, *moveX );
+			m_heading = ratan2( *moveY, *moveX ) & 4095;
 		}
 		else
 		{
diff --git a/source/enemy/nhcrab.cpp b/source/enemy/nhcrab.cpp
index dcf451e83..be23a3c5f 100644
--- a/source/enemy/nhcrab.cpp
+++ b/source/enemy/nhcrab.cpp
@@ -234,7 +234,7 @@ void CNpcHermitCrabEnemy::processMovementModifier( int _frames, s32 distX, s32 d
 	s32 xDist = testPos2.vx - testPos1.vx;
 	s32 yDist = testPos2.vy - testPos1.vy;
 
-	s16 heading = ratan2( yDist, xDist );
+	s16 heading = ratan2( yDist, xDist ) & 4095;
 
 	m_drawRotation = heading;
 
diff --git a/source/enemy/nmjfish.cpp b/source/enemy/nmjfish.cpp
index ee3c66886..fb6dcb217 100644
--- a/source/enemy/nmjfish.cpp
+++ b/source/enemy/nmjfish.cpp
@@ -104,15 +104,16 @@ void CNpcMotherJellyfishEnemy::setupWaypoints( sThingActor *ThisActor )
 	u16	*PntList=(u16*)MakePtr(ThisActor,sizeof(sThingActor));
 
 	u16 newXPos, newYPos;
+	u16 origXPos, origYPos;
 
 	s32 startX = 0;
 
 	m_npcPath.setWaypointCount( ThisActor->PointCount - 1 );
 
-	newXPos = (u16) *PntList;
+	origXPos = newXPos = (u16) *PntList;
 	setWaypointPtr( PntList );
 	PntList++;
-	newYPos = (u16) *PntList;
+	origYPos = newYPos = (u16) *PntList;
 	PntList++;
 
 	setStartPos( newXPos, newYPos );
@@ -130,7 +131,7 @@ void CNpcMotherJellyfishEnemy::setupWaypoints( sThingActor *ThisActor )
 
 			if ( pointNum == 1 )
 			{
-				setHeading( newXPos, newYPos );
+				setHeading( newXPos, newYPos, origXPos, origYPos );
 			}
 
 			if ( pointNum == ThisActor->PointCount - 2 )
diff --git a/source/enemy/npbug.cpp b/source/enemy/npbug.cpp
index 3ccfb1f2e..6613cfbb4 100644
--- a/source/enemy/npbug.cpp
+++ b/source/enemy/npbug.cpp
@@ -47,7 +47,7 @@ void CNpcPricklyBugEnemy::processMovementModifier( int _frames, s32 distX, s32 d
 	s32 xDist = testPos2.vx - testPos1.vx;
 	s32 yDist = testPos2.vy - testPos1.vy;
 
-	s16 heading = ratan2( yDist, xDist );
+	s16 heading = ratan2( yDist, xDist ) & 4095;
 
 	m_drawRotation = heading;
 }
diff --git a/source/enemy/npc.cpp b/source/enemy/npc.cpp
index dc69666fe..66b3409be 100644
--- a/source/enemy/npc.cpp
+++ b/source/enemy/npc.cpp
@@ -487,13 +487,14 @@ void CNpcEnemy::setupWaypoints( sThingActor *ThisActor )
 	u16	*PntList=(u16*)MakePtr(ThisActor,sizeof(sThingActor));
 
 	u16 newXPos, newYPos;
+	u16 origXPos, origYPos;
 
 	m_npcPath.setWaypointCount( ThisActor->PointCount - 1 );
 
-	newXPos = (u16) *PntList;
+	origXPos = newXPos = (u16) *PntList;
 	setWaypointPtr( PntList );
 	PntList++;
-	newYPos = (u16) *PntList;
+	origYPos = newYPos = (u16) *PntList;
 	PntList++;
 
 	setStartPos( newXPos, newYPos );
@@ -505,7 +506,7 @@ void CNpcEnemy::setupWaypoints( sThingActor *ThisActor )
 		newYPos = (u16) *PntList;
 		PntList++;
 
-		setHeading( newXPos, newYPos );
+		setHeading( newXPos, newYPos, origXPos, origYPos );
 	}
 
 	setThinkArea();
@@ -548,9 +549,9 @@ void CNpcEnemy::setStartPosHighRes( s32 xPos, s32 yPos )
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void CNpcEnemy::setHeading( s32 xPos, s32 yPos )
+void CNpcEnemy::setHeading( s32 xPos, s32 yPos, s32 xOrig, s32 yOrig )
 {
-	m_heading = ( ratan2( ( ( yPos << 4 ) + 16 ) - Pos.vy, ( ( xPos << 4 ) + 8 ) - Pos.vx ) ) & 4095;
+	m_heading = ( ratan2( yPos - yOrig, xPos - xOrig ) ) & 4095;
 }
 
 
@@ -1016,11 +1017,11 @@ bool CNpcEnemy::processSensor()
 
 							if ( abs( playerXDist ) < abs( xDistWaypoint ) )
 							{
-								s16 headingToPlayer = ratan2( playerYDist, playerXDist );
+								s16 headingToPlayer = ratan2( playerYDist, playerXDist ) & 4095;
 
 								s16 decDir, incDir, moveDist;
 
-								s32 headingToWaypoint = ratan2( yDistWaypoint, xDistWaypoint );
+								s32 headingToWaypoint = ratan2( yDistWaypoint, xDistWaypoint ) & 4095;
 
 								// check waypoint is in the same direction as the user
 
@@ -1511,7 +1512,7 @@ void CNpcEnemy::processEnemyCollision( CThing *thisThing )
 	s32 xDist = Pos.vx - otherPos.vx;
 	s32 yDist = Pos.vy - otherPos.vy;
 
-	s16 headingFromTarget = ratan2( yDist, xDist );
+	s16 headingFromTarget = ratan2( yDist, xDist ) & 4095;
 
 	if ( ( xDist > 0 && otherDelta.vx < 0 ) || ( xDist < 0 && otherDelta.vx > 0 ) )
 	{
@@ -1576,7 +1577,7 @@ void CNpcEnemy::processUserCollision( CThing *thisThing )
 	s32 xDist = Pos.vx - otherPos.vx;
 	s32 yDist = Pos.vy - otherPos.vy;
 
-	s16 headingFromTarget = ratan2( yDist, xDist );
+	s16 headingFromTarget = ratan2( yDist, xDist ) & 4095;
 
 	/*if ( ( xDist > 0 && otherDelta.vx < 0 ) || ( xDist < 0 && otherDelta.vx > 0 ) )
 	{
@@ -1623,7 +1624,7 @@ bool CNpcEnemy::processCoralBlowerMovement( int _frames, s32 xDist, s32 yDist, u
 	s32 moveX, moveY;
 	s16 headingToTarget;
 
-	headingToTarget = ratan2( yDist, xDist );
+	headingToTarget = ratan2( yDist, xDist ) & 4095;
 
 	s32 preShiftX = _frames * 5 * rcos( headingToTarget );
 	s32 preShiftY = _frames * 5 * rsin( headingToTarget );
diff --git a/source/enemy/npc.h b/source/enemy/npc.h
index 05f57cb53..c4b567e09 100644
--- a/source/enemy/npc.h
+++ b/source/enemy/npc.h
@@ -97,7 +97,7 @@ public:
 	NPC_UNIT_TYPE		getType()												{return( m_type );}
 	static NPC_UNIT_TYPE		getTypeFromMapEdit( u16 newType );
 	void				setHeading( s32 newHeading )							{m_heading = newHeading;}
-	virtual void		setHeading( s32 xPos, s32 yPos );
+	virtual void		setHeading( s32 xPos, s32 yPos, s32 xOrig, s32 yOrig );
 	void				setWaypointPtr( u16 *newPtr )							{m_npcPath.setWaypointPtr( newPtr );}
 	void				setWaypointCount( u8 newCount )							{m_npcPath.setWaypointCount( newCount );}
 	void				setPathType( u8 newType )								{m_npcPath.setPathType( newType );}
diff --git a/source/enemy/npcpath.cpp b/source/enemy/npcpath.cpp
index 445b58b1e..8d47f5833 100644
--- a/source/enemy/npcpath.cpp
+++ b/source/enemy/npcpath.cpp
@@ -298,7 +298,7 @@ s32 CNpcPath::think( DVECTOR const &currentPos, bool *pathComplete, bool *waypoi
 		*distY = ( ( *waypoint << 4 ) + 16 ) - currentPos.vy;
 	}
 
-	s32 headingToTarget = ratan2( *distY, *distX );
+	s32 headingToTarget = ratan2( *distY, *distX ) & 4095;
 
 	return( headingToTarget );
 }
diff --git a/source/enemy/nscrab.cpp b/source/enemy/nscrab.cpp
index 60be251a6..0a41b69f2 100644
--- a/source/enemy/nscrab.cpp
+++ b/source/enemy/nscrab.cpp
@@ -341,7 +341,7 @@ void CNpcSpiderCrabEnemy::processMovementModifier( int _frames, s32 distX, s32 d
 	s32 xDist = testPos2.vx - testPos1.vx;
 	s32 yDist = testPos2.vy - testPos1.vy;
 
-	s16 heading = ratan2( yDist, xDist );
+	s16 heading = ratan2( yDist, xDist ) & 4095;
 
 	m_drawRotation = heading;
 }
diff --git a/source/enemy/nsjback.cpp b/source/enemy/nsjback.cpp
index 6bd728a4c..052dae89c 100644
--- a/source/enemy/nsjback.cpp
+++ b/source/enemy/nsjback.cpp
@@ -92,6 +92,8 @@ void CNpcSmallJellyfishBackgroundEnemy::processMovement( int _frames )
 				{
 					m_targetHeading += -1024 + ( getRnd() % 2049 );
 				}
+
+				m_targetHeading &= 4095;
 			}
 		}
 	}
@@ -181,7 +183,7 @@ void CNpcSmallJellyfishBackgroundEnemy::processUserCollision( CThing *thisThing
 	s32 xDist = Pos.vx - otherPos.vx;
 	s32 yDist = Pos.vy - otherPos.vy;
 
-	s16 headingFromTarget = ratan2( yDist, xDist );
+	s16 headingFromTarget = ratan2( yDist, xDist ) & 4095;
 
 	if ( ( xDist > 0 && otherDelta.vx < 0 ) || ( xDist < 0 && otherDelta.vx > 0 ) )
 	{
diff --git a/source/enemy/nsjfish.cpp b/source/enemy/nsjfish.cpp
index 6a0d68150..ce6b71c14 100644
--- a/source/enemy/nsjfish.cpp
+++ b/source/enemy/nsjfish.cpp
@@ -137,7 +137,7 @@ void CNpcSmallJellyfishEnemy::processClose( int _frames )
 				m_frame = 0;
 			}
 
-			s16 headingToPlayer = ratan2( playerYDist, playerXDist );
+			s16 headingToPlayer = ratan2( playerYDist, playerXDist ) & 4095;
 
 			if ( m_evadeClockwise )
 			{
diff --git a/source/enemy/nsklfish.cpp b/source/enemy/nsklfish.cpp
index cfd0d435e..849e05a89 100644
--- a/source/enemy/nsklfish.cpp
+++ b/source/enemy/nsklfish.cpp
@@ -92,7 +92,7 @@ void CNpcSkeletalFishEnemy::processClose( int _frames )
 		m_chargeTime += _frames;
 	}
 
-	s16 headingToPlayer = ratan2( playerYDist, playerXDist );
+	s16 headingToPlayer = ratan2( playerYDist, playerXDist ) & 4095;
 
 	if ( !m_animPlaying )
 	{
diff --git a/source/enemy/nsshark.cpp b/source/enemy/nsshark.cpp
index 8aa105215..ee81de2ac 100644
--- a/source/enemy/nsshark.cpp
+++ b/source/enemy/nsshark.cpp
@@ -876,13 +876,14 @@ void CNpcSubSharkEnemy::setupWaypoints( sThingActor *ThisActor )
 	u16	*PntList=(u16*)MakePtr(ThisActor,sizeof(sThingActor));
 
 	u16 newXPos, newYPos;
+	u16 startXPos, startYPos;
 
 	m_npcPath.setWaypointCount( ThisActor->PointCount - 1 );
 
-	newXPos = (u16) *PntList;
+	startXPos = newXPos = (u16) *PntList;
 	setWaypointPtr( PntList );
 	PntList++;
-	newYPos = (u16) *PntList;
+	startYPos = newYPos = (u16) *PntList;
 	PntList++;
 
 	setStartPos( newXPos, newYPos );
@@ -894,7 +895,7 @@ void CNpcSubSharkEnemy::setupWaypoints( sThingActor *ThisActor )
 		newYPos = (u16) *PntList;
 		PntList++;
 
-		setHeading( newXPos, newYPos );
+		setHeading( newXPos, newYPos, startXPos, startYPos );
 	}
 
 	s32 minX, maxX, minY, maxY;
diff --git a/source/enemy/nssnake.cpp b/source/enemy/nssnake.cpp
index 3d2ce164d..edae6b8a3 100644
--- a/source/enemy/nssnake.cpp
+++ b/source/enemy/nssnake.cpp
@@ -626,7 +626,7 @@ void CNpcSeaSnakeEnemy::updateTail( DVECTOR &oldPos, int _frames )
 		s32 xDist = oldPos.vx - newPos->pos.vx;
 		s32 yDist = oldPos.vy - newPos->pos.vy;
 
-		s16 headingToTarget = ratan2( yDist, xDist );
+		s16 headingToTarget = ratan2( yDist, xDist ) & 4095;
 
 		DVECTOR sinPos;
 
@@ -684,7 +684,7 @@ void CNpcSeaSnakeEnemy::updateTail( DVECTOR &oldPos, int _frames )
 		s32 xDist = oldPos.vx - currentPos.vx;
 		s32 yDist = oldPos.vy - currentPos.vy;
 
-		s16 headingToPrev = ratan2( yDist, xDist );
+		s16 headingToPrev = ratan2( yDist, xDist ) & 4095;
 		s16 headingFromNext;
 		s16 heading = headingToPrev;
 
@@ -695,7 +695,7 @@ void CNpcSeaSnakeEnemy::updateTail( DVECTOR &oldPos, int _frames )
 			DVECTOR const &nextPos = m_segmentArray[segmentCount + 1].getPos();
 			xDist = currentPos.vx - nextPos.vx;
 			yDist = currentPos.vy - nextPos.vy;
-			headingFromNext = ratan2( yDist, xDist );
+			headingFromNext = ratan2( yDist, xDist ) & 4095;
 
 			s16 decDir, incDir, moveDist;
 
diff --git a/source/enemy/nworm.cpp b/source/enemy/nworm.cpp
index 7391352e6..4540209d7 100644
--- a/source/enemy/nworm.cpp
+++ b/source/enemy/nworm.cpp
@@ -247,7 +247,7 @@ void CNpcParasiticWormEnemy::processMovement( int _frames )
 		s32 xDist = oldPos.vx - newPos->pos.vx;
 		s32 yDist = oldPos.vy - newPos->pos.vy;
 
-		s16 headingToTarget = ratan2( yDist, xDist );
+		s16 headingToTarget = ratan2( yDist, xDist ) & 4095;
 
 		DVECTOR sinPos;
 
@@ -282,7 +282,7 @@ void CNpcParasiticWormEnemy::processMovement( int _frames )
 		s32 xDist = oldPos.vx - currentPos.vx;
 		s32 yDist = oldPos.vy - currentPos.vy;
 
-		s16 headingToPrev = ratan2( yDist, xDist );
+		s16 headingToPrev = ratan2( yDist, xDist ) & 4095;
 		s16 headingFromNext;
 		s16 heading = headingToPrev;
 
@@ -293,7 +293,7 @@ void CNpcParasiticWormEnemy::processMovement( int _frames )
 			DVECTOR const &nextPos = m_segmentArray[segmentCount + 1].getPos();
 			xDist = currentPos.vx - nextPos.vx;
 			yDist = currentPos.vy - nextPos.vy;
-			headingFromNext = ratan2( yDist, xDist );
+			headingFromNext = ratan2( yDist, xDist ) & 4095;
 
 			s16 decDir, incDir, moveDist;