diff --git a/dlls/alias.cpp b/dlls/alias.cpp
index cf2b8e42..bda9f8d0 100644
--- a/dlls/alias.cpp
+++ b/dlls/alias.cpp
@@ -160,7 +160,7 @@ int CInfoGroup::GetMember( const char* szMemberName )
 	if (!szMemberName)
 	{
 		ALERT(at_console,"info_group: GetMember called with null szMemberName!?\n");
-		return NULL;
+		return 0;
 	}
 	for (int i = 0; i < m_cMembers; i++)
 	{
@@ -183,7 +183,7 @@ int CInfoGroup::GetMember( const char* szMemberName )
 
 	ALERT(at_console,"info_group \"%s\" has no member called \"%s\".\n",STRING(pev->targetname),szMemberName);
 //	ALERT(at_console,"getMember: fail\n");
-	return NULL;
+	return 0;
 }
 
 /*********************
diff --git a/dlls/barney.cpp b/dlls/barney.cpp
index a6f3e6c5..eba8545b 100644
--- a/dlls/barney.cpp
+++ b/dlls/barney.cpp
@@ -713,7 +713,6 @@ Schedule_t *CBarney::GetScheduleOfType( int Type )
 	switch( Type )
 	{
 	case SCHED_ARM_WEAPON:
-		if ( m_hEnemy != NULL )
 		if( m_hEnemy != 0 )
 		{
 			// face enemy, then draw.
diff --git a/dlls/bigmomma.cpp b/dlls/bigmomma.cpp
index 05e55515..c7cccbcf 100644
--- a/dlls/bigmomma.cpp
+++ b/dlls/bigmomma.cpp
@@ -626,7 +626,7 @@ void CBigMomma::LaunchMortar( void )
 
 	if (m_pCine) // is a scripted_action making me shoot?
 	{
-		if (m_hTargetEnt != NULL) // don't check m_fTurnType- bigmomma can fire in any direction.
+		if (m_hTargetEnt != 0) // don't check m_fTurnType- bigmomma can fire in any direction.
 		{
 			vecLaunch = VecCheckSplatToss( pev, startPos, m_hTargetEnt->pev->origin, RANDOM_FLOAT( 150, 500 ) );
 		}
diff --git a/dlls/bullsquid.cpp b/dlls/bullsquid.cpp
index db403e5f..86c6168e 100644
--- a/dlls/bullsquid.cpp
+++ b/dlls/bullsquid.cpp
@@ -550,7 +550,7 @@ void CBullsquid::HandleAnimEvent( MonsterEvent_t *pEvent )
 				vecSpitOffset = ( pev->origin + vecSpitOffset );
 			if (m_pCine) // LRC- are we being told to do this by a scripted_action?
 			{
-				if (m_hTargetEnt != NULL && m_pCine->PreciseAttack())
+				if (m_hTargetEnt != 0 && m_pCine->PreciseAttack())
 					vecSpitDir = ( ( m_hTargetEnt->pev->origin ) - vecSpitOffset ).Normalize();
 				else
 					vecSpitDir = gpGlobals->v_forward;
diff --git a/dlls/cbase.h b/dlls/cbase.h
index 4e856cf5..4985ce03 100644
--- a/dlls/cbase.h
+++ b/dlls/cbase.h
@@ -100,7 +100,7 @@ typedef enum
 	USE_NOT = 6,
 } USE_TYPE;
 
-extern char* GetStringForUseType( USE_TYPE useType );
+extern const char *GetStringForUseType( USE_TYPE useType );
 
 extern void FireTargets( const char *targetName, CBaseEntity *pActivator, CBaseEntity *pCaller, USE_TYPE useType, float value );
 
diff --git a/dlls/combat.cpp b/dlls/combat.cpp
index ee1c374d..887811df 100644
--- a/dlls/combat.cpp
+++ b/dlls/combat.cpp
@@ -977,7 +977,7 @@ int CBaseMonster::TakeDamage( entvars_t *pevInflictor, entvars_t *pevAttacker, f
 			else if (m_iPlayerReact == 3)
 			{
 				// try to decide whether it was deliberate... if I have an enemy, assume it was just crossfire.
-				if ( m_hEnemy == NULL )
+				if ( m_hEnemy == 0 )
 				{
 					if ( (m_afMemory & bits_MEMORY_SUSPICIOUS) || UTIL_IsFacing( pevAttacker, pev->origin ) )
 						Remember( bits_MEMORY_PROVOKED );
diff --git a/dlls/controller.cpp b/dlls/controller.cpp
index 09d3e1f4..4fed2a3d 100644
--- a/dlls/controller.cpp
+++ b/dlls/controller.cpp
@@ -647,11 +647,11 @@ void CController::RunTask( Task_t *pTask )
 			Vector vecSrc = vecHand + pev->velocity * ( m_flShootTime - gpGlobals->time );
 			Vector vecDir;
 
-			if (m_pCine != NULL || m_hEnemy != NULL)
+			if (m_pCine != 0 || m_hEnemy != 0 )
 			{
-				if (m_pCine != NULL) // LRC- is this a script that's telling it to fire?
+				if (m_pCine != 0) // LRC- is this a script that's telling it to fire?
 				{
-					if (m_hTargetEnt != NULL && m_pCine->PreciseAttack())
+					if (m_hTargetEnt != 0 && m_pCine->PreciseAttack())
 					{
 						vecDir = (m_hTargetEnt->pev->origin - pev->origin).Normalize() * gSkillData.controllerSpeedBall;
 					}
@@ -661,7 +661,7 @@ void CController::RunTask( Task_t *pTask )
 						vecDir = gpGlobals->v_forward * gSkillData.controllerSpeedBall;
 					}
 				}
-				else if (m_hEnemy != NULL)
+				else if (m_hEnemy != 0)
 			{
 				if( HasConditions( bits_COND_SEE_ENEMY ) )
 				{
diff --git a/dlls/effects.cpp b/dlls/effects.cpp
index 385252d4..321d8de1 100644
--- a/dlls/effects.cpp
+++ b/dlls/effects.cpp
@@ -3966,7 +3966,7 @@ void CEnvELight::Use( CBaseEntity *pActivator, CBaseEntity *pCaller, USE_TYPE us
 	if (pev->target)
 	{
 		m_hAttach = UTIL_FindEntityByTargetname( NULL, STRING(pev->target), pActivator);
-		if (m_hAttach == NULL)
+		if (m_hAttach == 0)
 		{
 			ALERT(at_console, "env_elight \"%s\" can't find target %s\n", STRING(pev->targetname), STRING(pev->target));
 			return; // error?
@@ -3982,7 +3982,7 @@ void CEnvELight::Use( CBaseEntity *pActivator, CBaseEntity *pCaller, USE_TYPE us
 
 void CEnvELight::MakeLight(int iTime)
 {
-	if (m_hAttach == NULL)
+	if (m_hAttach == 0)
 	{
 		DontThink();
 		pev->takedamage = 0;
diff --git a/dlls/func_tank.cpp b/dlls/func_tank.cpp
index 1525932e..1c2175b1 100644
--- a/dlls/func_tank.cpp
+++ b/dlls/func_tank.cpp
@@ -1577,7 +1577,7 @@ void CFuncTankControls::Use( CBaseEntity *pActivator, CBaseEntity *pCaller, USE_
 			return;
 		// if I've already got a controller, or the player's already using
 		// another controls, then forget it.
-		if (m_active != FALSE || ((CBasePlayer*)pActivator)->m_pTank != NULL)
+		if (m_active != FALSE || ((CBasePlayer*)pActivator)->m_pTank != 0)
 			return;
 
 		//LRC- Now uses FindEntityByTargetname, so that aliases work.
diff --git a/dlls/hassassin.cpp b/dlls/hassassin.cpp
index cad0620a..71ff2469 100644
--- a/dlls/hassassin.cpp
+++ b/dlls/hassassin.cpp
@@ -186,7 +186,7 @@ void CHAssassin::SetYawSpeed( void )
 //=========================================================
 void CHAssassin::Shoot( void )
 {
-	if (m_hEnemy == NULL && !m_pCine) //LRC
+	if (m_hEnemy == 0 && !m_pCine) //LRC
 	{
 		return;
 	}
@@ -251,7 +251,7 @@ void CHAssassin::HandleAnimEvent( MonsterEvent_t *pEvent )
 			if (m_pCine && m_pCine->IsAction())
 			{
 				Vector vecToss;
-				if (m_pCine->PreciseAttack() && m_hTargetEnt != NULL)
+				if (m_pCine->PreciseAttack() && m_hTargetEnt != 0)
 				{
 					vecToss = VecCheckToss( pev, vecGunPosition, m_hTargetEnt->pev->origin, 0.5 );
 					//if (vecToss != g_vecZero)
@@ -282,7 +282,7 @@ void CHAssassin::HandleAnimEvent( MonsterEvent_t *pEvent )
 			if (m_pCine) //LRC...
 			{
 				pev->velocity = g_vecZero;
-				if (m_pCine->PreciseAttack() && m_hTargetEnt != NULL)
+				if (m_pCine->PreciseAttack() && m_hTargetEnt != 0)
 				{
 					Vector vecTemp = m_hTargetEnt->pev->origin;
 					vecTemp.y = vecTemp.y + 50; // put her feet on the target.
diff --git a/dlls/hgrunt.cpp b/dlls/hgrunt.cpp
index 0d106c3c..bc001bcb 100644
--- a/dlls/hgrunt.cpp
+++ b/dlls/hgrunt.cpp
@@ -789,7 +789,7 @@ Vector CHGrunt::GetGunPosition()
 //=========================================================
 void CHGrunt::Shoot( void )
 {
-	if (m_hEnemy == NULL && m_pCine == NULL) //LRC - scripts may fire when you have no enemy
+	if (m_hEnemy == 0 && m_pCine == 0) //LRC - scripts may fire when you have no enemy
 	{
 		return;
 	}
@@ -819,7 +819,7 @@ void CHGrunt::Shoot( void )
 //=========================================================
 void CHGrunt::Shotgun( void )
 {
-	if (m_hEnemy == NULL && m_pCine == NULL)
+	if (m_hEnemy == 0 && m_pCine == 0)
 	{
 		return;
 	}
@@ -893,7 +893,7 @@ void CHGrunt::HandleAnimEvent( MonsterEvent_t *pEvent )
 			if (m_pCine)
 			{
 				Vector vecToss = g_vecZero;
-				if (m_hTargetEnt != NULL && m_pCine->PreciseAttack())
+				if (m_hTargetEnt != 0 && m_pCine->PreciseAttack())
 				{
 					vecToss = VecCheckToss( pev, GetGunPosition(), m_hTargetEnt->pev->origin, 0.5 );
 				}
@@ -918,7 +918,7 @@ void CHGrunt::HandleAnimEvent( MonsterEvent_t *pEvent )
 			if (m_pCine)
 			{
 				Vector vecToss;
-				if (m_hTargetEnt != NULL && m_pCine->PreciseAttack())
+				if (m_hTargetEnt != 0 && m_pCine->PreciseAttack())
 					vecToss = VecCheckThrow( pev, GetGunPosition(), m_hTargetEnt->pev->origin, gSkillData.hgruntGrenadeSpeed, 0.5 );
 				else
 				{
diff --git a/dlls/islave_deamon.cpp b/dlls/islave_deamon.cpp
index 23d92d92..442efb77 100644
--- a/dlls/islave_deamon.cpp
+++ b/dlls/islave_deamon.cpp
@@ -51,7 +51,7 @@ public:
 	void HandleAnimEvent( MonsterEvent_t *pEvent );
 	BOOL CheckRangeAttack1 ( float flDot, float flDist );
 	BOOL CheckRangeAttack2 ( float flDot, float flDist );
-	void CallForHelp( char *szClassname, float flDist, EHANDLE hEnemy, Vector &vecLocation );
+	void CallForHelp( const char *szClassname, float flDist, EHANDLE hEnemy, Vector &vecLocation );
 	void TraceAttack( entvars_t *pevAttacker, float flDamage, Vector vecDir, TraceResult *ptr, int bitsDamageType);
 	int TakeDamage( entvars_t* pevInflictor, entvars_t* pevAttacker, float flDamage, int bitsDamageType);
 
@@ -160,7 +160,7 @@ int CISlave::IRelationship( CBaseEntity *pTarget )
 }
 
 
-void CISlave :: CallForHelp( char *szClassname, float flDist, EHANDLE hEnemy, Vector &vecLocation )
+void CISlave :: CallForHelp( const char *szClassname, float flDist, EHANDLE hEnemy, Vector &vecLocation )
 {
 	// ALERT( at_aiconsole, "help " );
 
@@ -191,7 +191,7 @@ void CISlave :: CallForHelp( char *szClassname, float flDist, EHANDLE hEnemy, Ve
 //=========================================================
 void CISlave :: AlertSound( void )
 {
-	if ( m_hEnemy != NULL )
+	if ( m_hEnemy != 0 )
 	{
 		SENTENCEG_PlayRndSz(ENT(pev), "SLV_ALERT", 0.85, ATTN_NORM, 0, m_voicePitch);
 
@@ -378,7 +378,7 @@ void CISlave :: HandleAnimEvent( MonsterEvent_t *pEvent )
 				MESSAGE_END( );
 
 			}
-			if (m_hDead != NULL)
+			if (m_hDead != 0)
 			{
 				WackBeam( -1, m_hDead );
 				WackBeam( 1, m_hDead );
@@ -399,7 +399,7 @@ void CISlave :: HandleAnimEvent( MonsterEvent_t *pEvent )
 		{
 			ClearBeams( );
 
-			if (m_hDead != NULL)
+			if (m_hDead != 0)
 			{
 				Vector vecDest = m_hDead->pev->origin + Vector( 0, 0, 38 );
 				TraceResult trace;
@@ -501,7 +501,7 @@ BOOL CISlave :: CheckRangeAttack2 ( float flDot, float flDist )
 			}
 		}
 	}
-	if (m_hDead != NULL)
+	if (m_hDead != 0)
 		return TRUE;
 	else
 		return FALSE;
diff --git a/dlls/locus.cpp b/dlls/locus.cpp
index 7186b602..2e90620b 100644
--- a/dlls/locus.cpp
+++ b/dlls/locus.cpp
@@ -117,7 +117,7 @@ void CLocusAlias::FlushChanges( void )
 
 CBaseEntity *CLocusAlias::FollowAlias( CBaseEntity *pFrom )
 {
-	if (m_hValue == NULL)
+	if (m_hValue == 0)
 		return NULL;
 	else if ( pFrom == NULL || (OFFSET(m_hValue->pev) > OFFSET(pFrom->pev)) )
 	{
diff --git a/dlls/monsters.cpp b/dlls/monsters.cpp
index d6f82463..f7d14728 100644
--- a/dlls/monsters.cpp
+++ b/dlls/monsters.cpp
@@ -3180,7 +3180,7 @@ BOOL CBaseMonster::FindLateralCover( const Vector &vecThreat, const Vector &vecV
 
 Vector CBaseMonster::ShootAtEnemy( const Vector &shootOrigin )
 {
-	if (m_pCine != NULL && m_hTargetEnt != NULL && (m_pCine->m_fTurnType == 1))
+	if (m_pCine != 0 && m_hTargetEnt != 0 && (m_pCine->m_fTurnType == 1))
 	{
 		Vector vecDest = ( m_hTargetEnt->pev->absmin + m_hTargetEnt->pev->absmax ) / 2;
 		return ( vecDest - shootOrigin ).Normalize();
diff --git a/dlls/player.cpp b/dlls/player.cpp
index 79977a77..b4a8e283 100644
--- a/dlls/player.cpp
+++ b/dlls/player.cpp
@@ -5133,7 +5133,7 @@ class CPlayerFreeze:public CBaseDelay
 {
 	void Use( CBaseEntity *pActivator, CBaseEntity *pCaller, USE_TYPE useType, float value );
 	void Think( void );
-	STATE GetState( void ) { return m_hActivator == NULL? STATE_OFF: STATE_ON; }
+	STATE GetState( void ) { return m_hActivator == 0 ? STATE_OFF : STATE_ON; }
 };
 
 void CPlayerFreeze::Use( CBaseEntity *pActivator, CBaseEntity *pCaller, USE_TYPE useType, float value )
diff --git a/dlls/scripted.cpp b/dlls/scripted.cpp
index 4d1a2995..fd01c945 100644
--- a/dlls/scripted.cpp
+++ b/dlls/scripted.cpp
@@ -369,29 +369,29 @@ void CCineMonster::PossessEntity( void )
 		{
 			// anything with that name?
 			pTarget->m_hTargetEnt = UTIL_FindEntityByTargetname(NULL, STRING(m_iszAttack), m_hActivator);
-			if ( pTarget->m_hTargetEnt == NULL )
+			if( pTarget->m_hTargetEnt == 0 )
 			{	// nothing. Anything with that classname?
 				while ((pTarget->m_hTargetEnt = UTIL_FindEntityInSphere( pTarget->m_hTargetEnt, pev->origin, m_flRadius )) != NULL)
-		{
+				{
 					if (FClassnameIs( pTarget->m_hTargetEnt->pev, STRING(m_iszAttack))) break;
+				}
 			}
-		}
-			if (pTarget->m_hTargetEnt == NULL)
+			if (pTarget->m_hTargetEnt == 0)
 			{	// nothing. Oh well.
 				ALERT(at_console,"%s %s has a missing \"turn target\": %s\n",STRING(pev->classname),STRING(pev->targetname),STRING(m_iszAttack));
 				pTarget->m_hTargetEnt = this;
-	}
-}
+			}
+		}
 		else
-{
+		{
 			pTarget->m_hTargetEnt = this;
 		}
 
 		if (m_iszMoveTarget)
-	{
+		{
 			// anything with that name?
 			pTarget->m_pGoalEnt = UTIL_FindEntityByTargetname(NULL, STRING(m_iszMoveTarget), m_hActivator);
-			if (pTarget->m_pGoalEnt == NULL)
+			if( pTarget->m_pGoalEnt == 0 )
 			{	// nothing. Oh well.
 				ALERT(at_console,"%s %s has a missing \"move target\": %s\n",STRING(pev->classname),STRING(pev->targetname),STRING(m_iszMoveTarget));
 				pTarget->m_pGoalEnt = this;
@@ -445,7 +445,7 @@ void CCineMonster::PossessEntity( void )
 
 // at the beginning of the level, set up the idle animation. --LRC
 void CCineMonster :: InitIdleThink( void )
-		{
+{
 	if ((m_hTargetEnt = FindEntity(STRING(m_iszEntity), NULL)) != NULL)
 			{
 		PossessEntity( );
diff --git a/dlls/squeakgrenade.cpp b/dlls/squeakgrenade.cpp
index e7b94994..5ad051d4 100644
--- a/dlls/squeakgrenade.cpp
+++ b/dlls/squeakgrenade.cpp
@@ -189,7 +189,7 @@ void CSqueakGrenade::Killed( entvars_t *pevAttacker, int iGib )
 		RadiusDamage( pev, pev, pev->dmg, CLASS_NONE, DMG_BLAST );
 
 	// reset owner so death message happens
-	if (m_hOwner != NULL)
+	if (m_hOwner != 0)
 		pev->owner = m_hOwner->edict();
 
 	CBaseMonster::Killed( pevAttacker, GIB_ALWAYS );
diff --git a/dlls/triggers.cpp b/dlls/triggers.cpp
index a715470a..607b7af1 100644
--- a/dlls/triggers.cpp
+++ b/dlls/triggers.cpp
@@ -1580,7 +1580,7 @@ public:
 	void Use ( CBaseEntity *pActivator, CBaseEntity *pCaller, USE_TYPE useType, float value );
 
 	void Affect (CBaseEntity *pTarget, USE_TYPE useType);
-	int GetActionFor( int iField, int iActive, USE_TYPE useType, char *szDebug );
+	int GetActionFor( int iField, int iActive, USE_TYPE useType, const char *szDebug );
 	void SetBoneController (float fController, int cnum, CBaseEntity *pTarget);
 
 	virtual int	ObjectCaps( void ) { return CBaseEntity :: ObjectCaps() & ~FCAP_ACROSS_TRANSITION; }
@@ -2054,7 +2054,7 @@ void CEnvCustomize :: Affect (CBaseEntity *pTarget, USE_TYPE useType)
 		ALERT(at_console, " ]\n");
 }
 
-int CEnvCustomize::GetActionFor( int iField, int iActive, USE_TYPE useType, char* szDebug)
+int CEnvCustomize::GetActionFor( int iField, int iActive, USE_TYPE useType, const char* szDebug)
 {
 	int iAction = iField;
 
@@ -3529,7 +3529,7 @@ int CChangeLevel::ChangeList( LEVELLIST *pLevelList, int maxList )
 	CBaseEntity *pChangelevel = UTIL_FindEntityByClassname( NULL, "trigger_changelevel" );
 
 	if ( !pChangelevel )
-		return NULL;
+		return 0;
 
 	while ( pChangelevel )
 	{
@@ -4595,7 +4595,7 @@ IMPLEMENT_SAVERESTORE(CMotionThread,CPointEntity);
 
 void CMotionThread::Think( void )
 {
-	if (m_hLocus == NULL || m_hTarget == NULL)
+	if( m_hLocus == 0 || m_hTarget == 0 )
 	{
 		if (pev->spawnflags & SF_MOTION_DEBUG)
 			ALERT(at_console, "motion_thread expires\n");
diff --git a/dlls/util.cpp b/dlls/util.cpp
index 287ee0e5..3d45d173 100644
--- a/dlls/util.cpp
+++ b/dlls/util.cpp
@@ -1984,7 +1984,7 @@ void UTIL_StripToken( const char *pKey, char *pDest )
 }
 
 
-char* GetStringForUseType( USE_TYPE useType )
+const char* GetStringForUseType( USE_TYPE useType )
 {
 	switch(useType)
 	{
@@ -1998,7 +1998,7 @@ char* GetStringForUseType( USE_TYPE useType )
 	}
 }
 
-char* GetStringForState( STATE state )
+const char *GetStringForState( STATE state )
 {
 	switch(state)
 	{
diff --git a/dlls/util.h b/dlls/util.h
index 4032798d..fdcf2417 100644
--- a/dlls/util.h
+++ b/dlls/util.h
@@ -209,7 +209,7 @@ typedef enum
 					// In_Use isn't very useful, I'll probably remove it.
 } STATE;
 
-extern char* GetStringForState( STATE state );
+extern const char *GetStringForState( STATE state );
 
 // Things that toggle (buttons/triggers/doors) need this
 typedef enum
@@ -614,4 +614,4 @@ int GetStdLightStyle (int iStyle); //LRC- declared here so it can be used by eve
 									// needs to deal with the standard lightstyles.
 // LRC- for aliases and groups
 CBaseEntity* UTIL_FollowReference( CBaseEntity* pStartEntity, const char* szName );
-#endif // UTIL_H
\ No newline at end of file
+#endif // UTIL_H