diff --git a/neo/cm/CollisionModel_local.h b/neo/cm/CollisionModel_local.h
index 42d12379..d7dce801 100644
--- a/neo/cm/CollisionModel_local.h
+++ b/neo/cm/CollisionModel_local.h
@@ -83,8 +83,10 @@ typedef struct cm_vertex_s
 {
 	idVec3					p;					// vertex point
 	int						checkcount;			// for multi-check avoidance
-	unsigned long			side;				// each bit tells at which side this vertex passes one of the trace model edges
-	unsigned long			sideSet;			// each bit tells if sidedness for the trace model edge has been calculated yet
+	// DG: use int instead of long for 64bit compatibility
+	unsigned int			side;				// each bit tells at which side this vertex passes one of the trace model edges
+	unsigned int			sideSet;			// each bit tells if sidedness for the trace model edge has been calculated yet
+	// DG end
 } cm_vertex_t;
 
 typedef struct cm_edge_s
@@ -92,8 +94,10 @@ typedef struct cm_edge_s
 	int						checkcount;			// for multi-check avoidance
 	unsigned short			internal;			// a trace model can never collide with internal edges
 	unsigned short			numUsers;			// number of polygons using this edge
-	unsigned long			side;				// each bit tells at which side of this edge one of the trace model vertices passes
-	unsigned long			sideSet;			// each bit tells if sidedness for the trace model vertex has been calculated yet
+	// DG: use int instead of long for 64bit compatibility
+	unsigned int			side;				// each bit tells at which side of this edge one of the trace model vertices passes
+	unsigned int			sideSet;			// each bit tells if sidedness for the trace model vertex has been calculated yet
+	// DG end
 	int						vertexNum[2];		// start and end point of edge
 	idVec3					normal;				// edge normal
 } cm_edge_t;
diff --git a/neo/d3xp/Pvs.h b/neo/d3xp/Pvs.h
index 2ed1b94e..2bc1b83f 100644
--- a/neo/d3xp/Pvs.h
+++ b/neo/d3xp/Pvs.h
@@ -104,9 +104,9 @@ private:
 	mutable pvsCurrent_t currentPVS[MAX_CURRENT_PVS];
 	// used to create PVS
 	int					portalVisBytes;
-	int					portalVisLongs;
+	int					portalVisLongs; // DG: Note: these are really ints now..
 	int					areaVisBytes;
-	int					areaVisLongs;
+	int					areaVisLongs;   // DG: Note: these are really ints now..
 	struct pvsPortal_s* pvsPortals;
 	struct pvsArea_s* 	pvsAreas;
 	
diff --git a/neo/d3xp/gamesys/Class.cpp b/neo/d3xp/gamesys/Class.cpp
index ac542088..e2ea595d 100644
--- a/neo/d3xp/gamesys/Class.cpp
+++ b/neo/d3xp/gamesys/Class.cpp
@@ -312,7 +312,9 @@ idClass::FindUninitializedMemory
 void idClass::FindUninitializedMemory()
 {
 #ifdef ID_DEBUG_UNINITIALIZED_MEMORY
-	unsigned long* ptr = ( ( unsigned long* )this ) - 1;
+	// DG: use int instead of long for 64bit compatibility
+	unsigned int* ptr = ( ( unsigned int* )this ) - 1;
+	// DG end
 	int size = *ptr;
 	assert( ( size & 3 ) == 0 );
 	size >>= 2;
diff --git a/neo/framework/Compressor.cpp b/neo/framework/Compressor.cpp
index 4916efa5..e386eb36 100644
--- a/neo/framework/Compressor.cpp
+++ b/neo/framework/Compressor.cpp
@@ -1726,7 +1726,9 @@ idCompressor_Arithmetic::GetCurrentCount
 */
 int idCompressor_Arithmetic::GetCurrentCount()
 {
-	return ( unsigned int )( ( ( ( ( long ) code - low ) + 1 ) * scale - 1 ) / ( ( ( long ) high - low ) + 1 ) );
+	// DG: use int instead of long for 64bit compatibility
+	return ( unsigned int )( ( ( ( ( int ) code - low ) + 1 ) * scale - 1 ) / ( ( ( int ) high - low ) + 1 ) );
+	// DG end
 }
 
 /*
@@ -1805,9 +1807,11 @@ idCompressor_Arithmetic::RemoveSymbolFromStream
 */
 void idCompressor_Arithmetic::RemoveSymbolFromStream( acSymbol_t* symbol )
 {
-	long range;
+	// DG: use int instead of long for 64bit compatibility
+	int range;
 	
-	range	= ( long )( high - low ) + 1;
+	range	= ( int )( high - low ) + 1;
+	// DG end
 	high	= low + ( unsigned short )( ( range * symbol->high ) / scale - 1 );
 	low		= low + ( unsigned short )( ( range * symbol->low ) / scale );
 	
diff --git a/neo/framework/DeclManager.cpp b/neo/framework/DeclManager.cpp
index bcd3af38..83072a50 100644
--- a/neo/framework/DeclManager.cpp
+++ b/neo/framework/DeclManager.cpp
@@ -286,7 +286,7 @@ typedef struct huffmanNode_s
 
 typedef struct huffmanCode_s
 {
-	unsigned long			bits[8];
+	unsigned int			bits[8]; // DG: use int instead of long for 64bit compatibility
 	int						numBits;
 } huffmanCode_t;
 
@@ -2721,4 +2721,4 @@ idDeclLocal::EverReferenced
 bool idDeclLocal::EverReferenced() const
 {
 	return everReferenced;
-}
\ No newline at end of file
+}
diff --git a/neo/framework/File.cpp b/neo/framework/File.cpp
index 183c2b08..426999d2 100644
--- a/neo/framework/File.cpp
+++ b/neo/framework/File.cpp
@@ -39,8 +39,9 @@ FS_WriteFloatString
 */
 int FS_WriteFloatString( char* buf, const char* fmt, va_list argPtr )
 {
-	long i;
-	unsigned long u;
+	// DG: replaced long with int for 64bit compatibility in the whole function
+	int i;
+	unsigned int u;
 	double f;
 	char* str;
 	int index;
@@ -84,27 +85,27 @@ int FS_WriteFloatString( char* buf, const char* fmt, va_list argPtr )
 						break;
 					case 'd':
 					case 'i':
-						i = va_arg( argPtr, long );
+						i = va_arg( argPtr, int );
 						index += sprintf( buf + index, format.c_str(), i );
 						break;
 					case 'u':
-						u = va_arg( argPtr, unsigned long );
+						u = va_arg( argPtr, unsigned int );
 						index += sprintf( buf + index, format.c_str(), u );
 						break;
 					case 'o':
-						u = va_arg( argPtr, unsigned long );
+						u = va_arg( argPtr, unsigned int );
 						index += sprintf( buf + index, format.c_str(), u );
 						break;
 					case 'x':
-						u = va_arg( argPtr, unsigned long );
+						u = va_arg( argPtr, unsigned int );
 						index += sprintf( buf + index, format.c_str(), u );
 						break;
 					case 'X':
-						u = va_arg( argPtr, unsigned long );
+						u = va_arg( argPtr, unsigned int );
 						index += sprintf( buf + index, format.c_str(), u );
 						break;
 					case 'c':
-						i = va_arg( argPtr, long );
+						i = va_arg( argPtr, int );
 						index += sprintf( buf + index, format.c_str(), ( char ) i );
 						break;
 					case 's':
@@ -150,6 +151,7 @@ int FS_WriteFloatString( char* buf, const char* fmt, va_list argPtr )
 	}
 	
 	return index;
+	// DG end
 }
 
 /*
diff --git a/neo/framework/FileSystem.cpp b/neo/framework/FileSystem.cpp
index 7c3c2d1d..d4353ac6 100644
--- a/neo/framework/FileSystem.cpp
+++ b/neo/framework/FileSystem.cpp
@@ -2797,7 +2797,7 @@ void idFileSystemLocal::CreateCRCsForResourceFileList( const idFileList& list )
 		}
 		
 		// All tables read, now seek to each one and calculate the CRC.
-		idTempArray< unsigned long > innerFileCRCs( numFileResources );
+		idTempArray< unsigned int > innerFileCRCs( numFileResources ); // DG: use int instead of long for 64bit compatibility
 		for( int innerFileIndex = 0; innerFileIndex < numFileResources; ++innerFileIndex )
 		{
 			const char* innerFileDataBegin = currentFile->GetDataPtr() + cacheEntries[innerFileIndex].offset;
@@ -2806,7 +2806,7 @@ void idFileSystemLocal::CreateCRCsForResourceFileList( const idFileList& list )
 		}
 		
 		// Get the CRC for all the CRCs.
-		const unsigned long totalCRC = CRC32_BlockChecksum( innerFileCRCs.Ptr(), innerFileCRCs.Size() );
+		const unsigned int totalCRC = CRC32_BlockChecksum( innerFileCRCs.Ptr(), innerFileCRCs.Size() ); // DG: use int instead of long for 64bit compatibility
 		
 		// Write the .crc file corresponding to the .resources file.
 		idStr crcFilename = list.GetFile( fileIndex );
diff --git a/neo/idlib/Base64.cpp b/neo/idlib/Base64.cpp
index 570228c3..8c58508c 100644
--- a/neo/idlib/Base64.cpp
+++ b/neo/idlib/Base64.cpp
@@ -44,7 +44,7 @@ static const char sixtet_to_base64[] =
 void idBase64::Encode( const byte* from, int size )
 {
 	int i, j;
-	unsigned long w;
+	unsigned int w; // DG: use int instead of long for 64bit compatibility
 	byte* to;
 	
 	EnsureAlloced( 4 * ( size + 3 ) / 3 + 2 ); // ratio and padding + trailing \0
@@ -101,7 +101,7 @@ idBase64::Decode
 */
 int idBase64::Decode( byte* to ) const
 {
-	unsigned long w;
+	unsigned int w; // DG: use int instead of long for 64bit compatibility
 	int i, j;
 	size_t n;
 	static char base64_to_sixtet[256];
diff --git a/neo/idlib/Parser.cpp b/neo/idlib/Parser.cpp
index d3b8c54f..bb5c1c32 100644
--- a/neo/idlib/Parser.cpp
+++ b/neo/idlib/Parser.cpp
@@ -1511,7 +1511,7 @@ typedef struct operator_s
 
 typedef struct value_s
 {
-	signed long int intvalue;
+	signed int intvalue; // DG: use int instead of long for 64bit compatibility
 	double floatvalue;
 	int parentheses;
 	struct value_s* prev, *next;
@@ -1606,7 +1606,7 @@ int PC_OperatorPriority( int op )
 
 #define FreeOperator(op)
 
-int idParser::EvaluateTokens( idToken* tokens, signed long int* intvalue, double* floatvalue, int integer )
+int idParser::EvaluateTokens( idToken* tokens, signed int* intvalue, double* floatvalue, int integer )
 {
 	operator_t* o, *firstoperator, *lastoperator;
 	value_t* v, *firstvalue, *lastvalue, *v1, *v2;
@@ -2117,7 +2117,7 @@ int idParser::EvaluateTokens( idToken* tokens, signed long int* intvalue, double
 idParser::Evaluate
 ================
 */
-int idParser::Evaluate( signed long int* intvalue, double* floatvalue, int integer )
+int idParser::Evaluate( signed int* intvalue, double* floatvalue, int integer )
 {
 	idToken token, *firsttoken, *lasttoken;
 	idToken* t, *nexttoken;
@@ -2224,7 +2224,7 @@ int idParser::Evaluate( signed long int* intvalue, double* floatvalue, int integ
 idParser::DollarEvaluate
 ================
 */
-int idParser::DollarEvaluate( signed long int* intvalue, double* floatvalue, int integer )
+int idParser::DollarEvaluate( signed int* intvalue, double* floatvalue, int integer )
 {
 	int indent, defined = false;
 	idToken token, *firsttoken, *lasttoken;
@@ -2345,7 +2345,7 @@ idParser::Directive_elif
 */
 int idParser::Directive_elif()
 {
-	signed long int value;
+	signed int value; // DG: use int instead of long for 64bit compatibility
 	int type, skip;
 	
 	idParser::PopIndent( &type, &skip );
@@ -2370,7 +2370,7 @@ idParser::Directive_if
 */
 int idParser::Directive_if()
 {
-	signed long int value;
+	signed int value; // DG: use int instead of long for 64bit compatibility
 	int skip;
 	
 	if( !idParser::Evaluate( &value, NULL, true ) )
@@ -2477,7 +2477,7 @@ idParser::Directive_eval
 */
 int idParser::Directive_eval()
 {
-	signed long int value;
+	signed int value; // DG: use int instead of long for 64bit compatibility
 	idToken token;
 	char buf[128];
 	
@@ -2644,7 +2644,7 @@ idParser::DollarDirective_evalint
 */
 int idParser::DollarDirective_evalint()
 {
-	signed long int value;
+	signed int value; // DG: use int instead of long for 64bit compatibility
 	idToken token;
 	char buf[128];
 	
@@ -2697,7 +2697,7 @@ int idParser::DollarDirective_evalfloat()
 	token = buf;
 	token.type = TT_NUMBER;
 	token.subtype = TT_FLOAT | TT_LONG | TT_DECIMAL | TT_VALUESVALID;
-	token.intvalue = ( unsigned long ) fabs( value );
+	token.intvalue = ( unsigned int ) fabs( value ); // DG: use int instead of long for 64bit compatibility
 	token.floatvalue = fabs( value );
 	idParser::UnreadSourceToken( &token );
 	if( value < 0 )
diff --git a/neo/idlib/Parser.h b/neo/idlib/Parser.h
index cdf44160..70aef498 100644
--- a/neo/idlib/Parser.h
+++ b/neo/idlib/Parser.h
@@ -232,9 +232,11 @@ private:
 	int				Directive_ifndef();
 	int				Directive_else();
 	int				Directive_endif();
-	int				EvaluateTokens( idToken* tokens, signed long int* intvalue, double* floatvalue, int integer );
-	int				Evaluate( signed long int* intvalue, double* floatvalue, int integer );
-	int				DollarEvaluate( signed long int* intvalue, double* floatvalue, int integer );
+	// DG: use int instead of long for 64bit compatibility
+	int				EvaluateTokens( idToken* tokens, signed int* intvalue, double* floatvalue, int integer );
+	int				Evaluate( signed int* intvalue, double* floatvalue, int integer );
+	int				DollarEvaluate( signed int* intvalue, double* floatvalue, int integer );
+	// DG end
 	int				Directive_define();
 	int				Directive_elif();
 	int				Directive_if();
diff --git a/neo/idlib/Str.cpp b/neo/idlib/Str.cpp
index c3e77b9e..cbddf776 100644
--- a/neo/idlib/Str.cpp
+++ b/neo/idlib/Str.cpp
@@ -1043,7 +1043,7 @@ idStr::FileNameHash
 int idStr::FileNameHash() const
 {
 	int		i;
-	long	hash;
+	int		hash; // DG: use int instead of long for 64bit compatibility
 	char	letter;
 	
 	hash = 0;
@@ -1059,7 +1059,7 @@ int idStr::FileNameHash() const
 		{
 			letter = '/';
 		}
-		hash += ( long )( letter ) * ( i + 119 );
+		hash += ( long )( letter ) * ( i + 119 ); // DG: use int instead of long for 64bit compatibility
 		i++;
 	}
 	hash &= ( FILE_HASH_SIZE - 1 );
diff --git a/neo/idlib/Token.h b/neo/idlib/Token.h
index fd000548..50254320 100644
--- a/neo/idlib/Token.h
+++ b/neo/idlib/Token.h
@@ -99,7 +99,9 @@ public:
 	void			NumberValue();				// calculate values for a TT_NUMBER
 	
 private:
-	unsigned long	intvalue;							// integer value
+	// DG: use int instead of long for 64bit compatibility
+	unsigned int	intvalue;							// integer value
+	// DG end
 	double			floatvalue;							// floating point value
 	const char* 	whiteSpaceStart_p;					// start of white space before token, only used by idLexer
 	const char* 	whiteSpaceEnd_p;					// end of white space before token, only used by idLexer
diff --git a/neo/idlib/math/Random.h b/neo/idlib/math/Random.h
index e920a9dd..b44ad378 100644
--- a/neo/idlib/math/Random.h
+++ b/neo/idlib/math/Random.h
@@ -108,10 +108,11 @@ ID_INLINE float idRandom::CRandomFloat()
 class idRandom2
 {
 public:
-	idRandom2( unsigned long seed = 0 );
+	// DG: use int instead of long for 64bit compatibility in this whole class
+	idRandom2( unsigned int seed = 0 );
 	
-	void					SetSeed( unsigned long seed );
-	unsigned long			GetSeed() const;
+	void					SetSeed( unsigned int seed );
+	unsigned int			GetSeed() const;
 	
 	int						RandomInt();			// random integer in the range [0, MAX_RAND]
 	int						RandomInt( int max );		// random integer in the range [0, max]
@@ -121,23 +122,23 @@ public:
 	static const int		MAX_RAND = 0x7fff;
 	
 private:
-	unsigned long			seed;
+	unsigned int			seed;
 	
-	static const unsigned long	IEEE_ONE = 0x3f800000;
-	static const unsigned long	IEEE_MASK = 0x007fffff;
+	static const unsigned int	IEEE_ONE = 0x3f800000;
+	static const unsigned int	IEEE_MASK = 0x007fffff;
 };
 
-ID_INLINE idRandom2::idRandom2( unsigned long seed )
+ID_INLINE idRandom2::idRandom2( unsigned int seed )
 {
 	this->seed = seed;
 }
 
-ID_INLINE void idRandom2::SetSeed( unsigned long seed )
+ID_INLINE void idRandom2::SetSeed( unsigned int seed )
 {
 	this->seed = seed;
 }
 
-ID_INLINE unsigned long idRandom2::GetSeed() const
+ID_INLINE unsigned int idRandom2::GetSeed() const
 {
 	return seed;
 }
@@ -159,7 +160,7 @@ ID_INLINE int idRandom2::RandomInt( int max )
 
 ID_INLINE float idRandom2::RandomFloat()
 {
-	unsigned long i;
+	unsigned int i;
 	seed = 1664525L * seed + 1013904223L;
 	i = idRandom2::IEEE_ONE | ( seed & idRandom2::IEEE_MASK );
 	return ( ( *( float* )&i ) - 1.0f );
@@ -167,10 +168,11 @@ ID_INLINE float idRandom2::RandomFloat()
 
 ID_INLINE float idRandom2::CRandomFloat()
 {
-	unsigned long i;
+	unsigned int i;
 	seed = 1664525L * seed + 1013904223L;
 	i = idRandom2::IEEE_ONE | ( seed & idRandom2::IEEE_MASK );
 	return ( 2.0f * ( *( float* )&i ) - 3.0f );
 }
+// DG end
 
 #endif /* !__MATH_RANDOM_H__ */
diff --git a/neo/idlib/math/Simd.cpp b/neo/idlib/math/Simd.cpp
index a88215cf..e29c6651 100644
--- a/neo/idlib/math/Simd.cpp
+++ b/neo/idlib/math/Simd.cpp
@@ -124,7 +124,7 @@ void idSIMD::Shutdown() {
 
 idSIMDProcessor *p_simd;
 idSIMDProcessor *p_generic;
-long baseClocks = 0;
+int baseClocks = 0; // DG: use int instead of long for 64bit compatibility
 
 #if defined(_MSC_VER) && defined(_M_IX86)
 #define TIME_TYPE int
diff --git a/neo/idlib/math/Simd_SSE.cpp b/neo/idlib/math/Simd_SSE.cpp
index 8970c4fa..93c4a742 100644
--- a/neo/idlib/math/Simd_SSE.cpp
+++ b/neo/idlib/math/Simd_SSE.cpp
@@ -280,13 +280,17 @@ void VPCALL idSIMD_SSE::BlendJoints( idJointQuat* joints, const idJointQuat* ble
 		float omega;
 		float scale0;
 		float scale1;
-		unsigned long signBit;
+		// DG: use int instead of long for 64bit compatibility
+		unsigned int signBit;
+		// DG end
 		
 		cosom = jointQuat.x * blendQuat.x + jointQuat.y * blendQuat.y + jointQuat.z * blendQuat.z + jointQuat.w * blendQuat.w;
 		
-		signBit = ( *( unsigned long* )&cosom ) & ( 1 << 31 );
+		// DG: use int instead of long for 64bit compatibility
+		signBit = ( *( unsigned int* )&cosom ) & ( 1 << 31 );
 		
-		( *( unsigned long* )&cosom ) ^= signBit;
+		( *( unsigned int* )&cosom ) ^= signBit;
+		// DG end
 		
 		scale0 = 1.0f - cosom * cosom;
 		scale0 = ( scale0 <= 0.0f ) ? 1e-10f : scale0;
@@ -295,7 +299,7 @@ void VPCALL idSIMD_SSE::BlendJoints( idJointQuat* joints, const idJointQuat* ble
 		scale0 = idMath::Sin16( ( 1.0f - lerp ) * omega ) * sinom;
 		scale1 = idMath::Sin16( lerp * omega ) * sinom;
 		
-		( *( unsigned long* )&scale1 ) ^= signBit;
+		( *( unsigned int* )&scale1 ) ^= signBit; // DG: use int instead of long for 64bit compatibility
 		
 		jointQuat.x = scale0 * jointQuat.x + scale1 * blendQuat.x;
 		jointQuat.y = scale0 * jointQuat.y + scale1 * blendQuat.y;
diff --git a/neo/idlib/sys/sys_types.h b/neo/idlib/sys/sys_types.h
index 5fa55071..e49551a6 100644
--- a/neo/idlib/sys/sys_types.h
+++ b/neo/idlib/sys/sys_types.h
@@ -40,7 +40,7 @@ typedef unsigned char		byte;		// 8 bits
 typedef unsigned short		word;		// 16 bits
 typedef unsigned int		dword;		// 32 bits
 typedef unsigned int		uint;
-typedef unsigned long		ulong;
+// typedef unsigned long		ulong; // DG: long should be avoided.
 
 typedef signed char			int8;
 typedef unsigned char		uint8;
diff --git a/neo/sys/sys_lobby.cpp b/neo/sys/sys_lobby.cpp
index f025480b..a2a03f3a 100644
--- a/neo/sys/sys_lobby.cpp
+++ b/neo/sys/sys_lobby.cpp
@@ -1573,7 +1573,7 @@ void idLobby::SendConnectionRequest()
 	idBitMsg msg( buffer, sizeof( buffer ) );
 	
 	// Add the current version info to the handshake
-	const unsigned long localChecksum = NetGetVersionChecksum();
+	const unsigned int localChecksum = NetGetVersionChecksum(); // DG: use int instead of long for 64bit compatibility
 	
 	NET_VERBOSE_PRINT( "NET: version = %i\n", localChecksum );
 	
@@ -1754,11 +1754,11 @@ idLobby::CheckVersion
 */
 bool idLobby::CheckVersion( idBitMsg& msg, lobbyAddress_t peerAddress )
 {
-	const unsigned long remoteChecksum = msg.ReadLong();
+	const unsigned int remoteChecksum = msg.ReadLong(); // DG: use int instead of long for 64bit compatibility
 	
 	if( net_checkVersion.GetInteger() == 1 )
 	{
-		const unsigned long localChecksum = NetGetVersionChecksum();
+		const unsigned int localChecksum = NetGetVersionChecksum(); // DG: use int instead of long for 64bit compatibility
 		
 		NET_VERBOSE_PRINT( "NET: Comparing handshake version - localChecksum = %i, remoteChecksum = %i\n", localChecksum, remoteChecksum );
 		return ( remoteChecksum == localChecksum );
@@ -2312,7 +2312,9 @@ uint32 idLobby::GetPartyTokenAsHost()
 	{
 		// I don't know if this is mathematically sound, but it seems reasonable.
 		// Don't do this at app startup (i.e. in the constructor) or it will be a lot less random.
-		unsigned long seed = Sys_Milliseconds(); // time app has been running
+		// DG: use int instead of long for 64bit compatibility
+		unsigned int seed = Sys_Milliseconds(); // time app has been running
+		// DG end
 		idLocalUser* masterUser = session->GetSignInManager().GetMasterLocalUser();
 		if( masterUser != NULL )
 		{
@@ -2865,7 +2867,7 @@ void idLobby::HandleReliableMsg( int p, idBitMsg& msg )
 		// This message is sent from the peers to state they are done loading the map
 		VERIFY_CONNECTED_PEER( p, actingGameStateLobbyType, RELIABLE_LOADING_DONE );
 		
-		unsigned long networkChecksum = 0;
+		unsigned int networkChecksum = 0; // DG: use int instead of long for 64bit compatibility
 		networkChecksum = msg.ReadLong();
 		
 		peer.networkChecksum = networkChecksum;
diff --git a/neo/sys/sys_lobby.h b/neo/sys/sys_lobby.h
index ba58ed0c..c1efb62a 100644
--- a/neo/sys/sys_lobby.h
+++ b/neo/sys/sys_lobby.h
@@ -334,7 +334,9 @@ public:
 		int					lastProcTime;				// Used to determine when a packet was processed for sending to this peer
 		int					lastInBandProcTime;			// Last time a in-band packet was processed for sending
 		int					lastFragmentSendTime;		// Last time a fragment was sent out (fragments are processed msg's, waiting to be fully sent)
-		unsigned long		networkChecksum;			// Checksum used to determine if a peer loaded the network resources the EXACT same as the server did
+		// DG: use int instead of long for 64bit compatibility
+		unsigned int		networkChecksum;			// Checksum used to determine if a peer loaded the network resources the EXACT same as the server did
+		// DG end
 		int					pauseSnapshots;
 		
 		lobbyAddress_t	address;
diff --git a/neo/sys/sys_public.h b/neo/sys/sys_public.h
index cc1f2435..5e77a4d3 100644
--- a/neo/sys/sys_public.h
+++ b/neo/sys/sys_public.h
@@ -426,7 +426,7 @@ struct sysMemoryStats_t
 	int availExtendedVirtual;
 };
 
-typedef unsigned long address_t;
+// typedef unsigned long address_t; // DG: this isn't even used
 
 void			Sys_Init();
 void			Sys_Shutdown();
diff --git a/neo/sys/sys_session_local.cpp b/neo/sys/sys_session_local.cpp
index af0fed51..3cca6fa5 100644
--- a/neo/sys/sys_session_local.cpp
+++ b/neo/sys/sys_session_local.cpp
@@ -4592,7 +4592,7 @@ void idSessionLocal::ListServersCommon()
 	idBitMsg msg( buffer, sizeof( buffer ) );
 	
 	// Add the current version info to the query
-	const unsigned long localChecksum = NetGetVersionChecksum();
+	const unsigned int localChecksum = NetGetVersionChecksum(); // DG: use int instead of long for 64bit compatibility
 	
 	NET_VERBOSE_PRINT( "ListServers: Hash checksum: %i, broadcasting to: %s\n", localChecksum, address.ToString() );
 	
@@ -4614,8 +4614,10 @@ void idSessionLocal::HandleDedicatedServerQueryRequest( lobbyAddress_t& remoteAd
 	
 	bool canJoin = true;
 	
-	const unsigned long localChecksum = NetGetVersionChecksum();
-	const unsigned long remoteChecksum = msg.ReadLong();
+	// DG: use int instead of long for 64bit compatibility
+	const unsigned int localChecksum = NetGetVersionChecksum();
+	const unsigned int remoteChecksum = msg.ReadLong();
+	// DG end
 	
 	if( remoteChecksum != localChecksum )
 	{