diff --git a/public/datamap.h b/public/datamap.h
index de3b3e93..537936ab 100644
--- a/public/datamap.h
+++ b/public/datamap.h
@@ -120,10 +120,6 @@ DECLARE_FIELD_SIZE( FIELD_MODELINDEX,	sizeof(int) )
 DECLARE_FIELD_SIZE( FIELD_MATERIALINDEX,	sizeof(int) )
 
 
-#ifndef offsetof
-#define offsetof(s,m)	(size_t)&(((s *)0)->m)
-#endif
-
 #define ARRAYSIZE2D(p)		(sizeof(p)/sizeof(p[0][0]))
 #define SIZE_OF_ARRAY(p)	_ARRAYSIZE(p)
 
diff --git a/public/studio.h b/public/studio.h
index f7612ae5..848b967f 100644
--- a/public/studio.h
+++ b/public/studio.h
@@ -28,10 +28,6 @@
 #include "localflexcontroller.h"
 
 
-#ifndef offsetof
-#define offsetof(s,m)	(size_t)&(((s *)0)->m)
-#endif
-
 #define STUDIO_ENABLE_PERF_COUNTERS
 
 #define STUDIO_SEQUENCE_ACTIVITY_LOOKUPS_ARE_SLOW 0 
diff --git a/public/tier0/platform.h b/public/tier0/platform.h
index 1fad3681..6f46723a 100644
--- a/public/tier0/platform.h
+++ b/public/tier0/platform.h
@@ -252,6 +252,17 @@ typedef void * HINSTANCE;
 #define MAX_PATH  260
 #endif
 
+
+#ifdef GNUC
+#undef offsetof
+//#define offsetof( type, var ) __builtin_offsetof( type, var ) 
+#define offsetof(s,m)	(size_t)&(((s *)0)->m)
+#else
+#undef offsetof
+#define offsetof(s,m)	(size_t)&(((s *)0)->m)
+#endif
+
+
 #define ALIGN_VALUE( val, alignment ) ( ( val + alignment - 1 ) & ~( alignment - 1 ) ) //  need macro for constant expression
 
 // Used to step into the debugger
diff --git a/public/vgui_controls/MessageMap.h b/public/vgui_controls/MessageMap.h
index 63eee288..7f0f5c51 100644
--- a/public/vgui_controls/MessageMap.h
+++ b/public/vgui_controls/MessageMap.h
@@ -22,10 +22,6 @@ namespace vgui
 
 ////////////// MESSAGEMAP DEFINITIONS //////////////
 
-#ifndef offsetof
-#define offsetof(s,m)	(size_t)&(((s *)0)->m)
-#endif
-
 #ifndef ARRAYSIZE
 #define ARRAYSIZE(p)	(sizeof(p)/sizeof(p[0]))
 #endif