diff --git a/common/xbox/xboxstubs.h b/common/xbox/xboxstubs.h
index fa65d6a8..1392297b 100644
--- a/common/xbox/xboxstubs.h
+++ b/common/xbox/xboxstubs.h
@@ -329,7 +329,7 @@ enum XUSER_SIGNIN_STATE
 
 #if (defined(POSIX))
 typedef size_t ULONG_PTR;
-#else
+#elif !(defined(WIN64))
 typedef _W64 unsigned long ULONG_PTR;
 #endif
 typedef ULONG_PTR DWORD_PTR, *PDWORD_PTR;
diff --git a/lib/public/win64/interfaces.lib b/lib/public/win64/interfaces.lib
new file mode 100644
index 00000000..8be90e0e
Binary files /dev/null and b/lib/public/win64/interfaces.lib differ
diff --git a/lib/public/win64/mathlib.lib b/lib/public/win64/mathlib.lib
new file mode 100644
index 00000000..2db1fb3b
Binary files /dev/null and b/lib/public/win64/mathlib.lib differ
diff --git a/lib/public/win64/tier0.lib b/lib/public/win64/tier0.lib
new file mode 100644
index 00000000..4e87eb41
Binary files /dev/null and b/lib/public/win64/tier0.lib differ
diff --git a/lib/public/win64/tier1.lib b/lib/public/win64/tier1.lib
new file mode 100644
index 00000000..46290467
Binary files /dev/null and b/lib/public/win64/tier1.lib differ
diff --git a/lib/public/win64/vstdlib.lib b/lib/public/win64/vstdlib.lib
new file mode 100644
index 00000000..da94e3ab
Binary files /dev/null and b/lib/public/win64/vstdlib.lib differ
diff --git a/mathlib/imagequant.cpp b/mathlib/imagequant.cpp
index ce712427..783ca999 100644
--- a/mathlib/imagequant.cpp
+++ b/mathlib/imagequant.cpp
@@ -57,7 +57,7 @@ void ColorQuantize(uint8 const *Image,
 	{
 		struct QuantizedValue *v=FindQNode(q,p);
 		if (v)
-			for(int c=0;c<3;c++)
+			for(c=0;c<3;c++)
 				out_palette[p*3+c]=v->Mean[c];
 	}
 	memset(Error,0,sizeof(Error));
diff --git a/mathlib/mathlib_base.cpp b/mathlib/mathlib_base.cpp
index d8068ea6..8d017a4c 100644
--- a/mathlib/mathlib_base.cpp
+++ b/mathlib/mathlib_base.cpp
@@ -3236,6 +3236,7 @@ void MathLib_Init( float gamma, float texGamma, float brightness, int overbright
 	{
 		s_bSSEEnabled = true;
 
+#ifndef _WIN64
 		// Select the SSE specific routines if available
 		pfVectorNormalizeFast = _SSE_VectorNormalizeFast;
 		pfInvRSquared = _SSE_InvRSquared;
@@ -3245,6 +3246,7 @@ void MathLib_Init( float gamma, float texGamma, float brightness, int overbright
 #ifdef _WIN32
 		pfFastSinCos = _SSE_SinCos;
 		pfFastCos = _SSE_cos;
+#endif
 #endif
 	}
 	else
@@ -3255,7 +3257,7 @@ void MathLib_Init( float gamma, float texGamma, float brightness, int overbright
 	if ( bAllowSSE2 && pi.m_bSSE2 )
 	{
 		s_bSSE2Enabled = true;
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(_WIN64)
 		pfFastSinCos = _SSE2_SinCos;
 		pfFastCos = _SSE2_cos;
 #endif
diff --git a/mathlib/quantize.cpp b/mathlib/quantize.cpp
index 2f4b64f2..aec1a3ce 100644
--- a/mathlib/quantize.cpp
+++ b/mathlib/quantize.cpp
@@ -198,8 +198,8 @@ static void UpdateStats(struct QuantizedValue *v)
 		N+=s->Count;
 		for(j=0;j<current_ndims;j++)
 		{
-			uint8 v=s->Value[j];
-			Means[j]+=v*s->Count;
+			uint8 v2=s->Value[j];
+			Means[j]+=v2*s->Count;
 		}
 	}
 	for(j=0;j<current_ndims;j++)
@@ -316,7 +316,7 @@ static void SubdivideNode(struct QuantizedValue *n, int whichdim)
 		// extrema instead. LocalMean[i][0] will be the point with the lowest
 		// value on the dimension and LocalMean[i][1] the one with the lowest
 		// value.
-		for(int i=0;i<current_ndims;i++)
+		for(i=0;i<current_ndims;i++)
 		{
 			LocalMean[i][0]=minS->Value[i];
 			LocalMean[i][1]=maxS->Value[i];
diff --git a/mathlib/sse.cpp b/mathlib/sse.cpp
index d39c24f8..b984941c 100644
--- a/mathlib/sse.cpp
+++ b/mathlib/sse.cpp
@@ -16,6 +16,9 @@
 // memdbgon must be the last include file in a .cpp file!!!
 #include "tier0/memdbgon.h"
 
+#ifndef COMPILER_MSVC64
+// Implement for 64-bit Windows if needed.
+
 static const uint32 _sincos_masks[]	  = { (uint32)0x0,  (uint32)~0x0 };
 static const uint32 _sincos_inv_masks[] = { (uint32)~0x0, (uint32)0x0 };
 
@@ -843,3 +846,4 @@ vec_t DotProduct (const vec_t *a, const vec_t *c)
 }
 */
 
+#endif // COMPILER_MSVC64 
diff --git a/public/bitmap/imageformat.h b/public/bitmap/imageformat.h
index b5bdf43b..cd096e9c 100644
--- a/public/bitmap/imageformat.h
+++ b/public/bitmap/imageformat.h
@@ -25,7 +25,6 @@ enum NormalDecodeMode_t
 // Forward declaration
 #ifdef _WIN32
 typedef enum _D3DFORMAT D3DFORMAT;
-typedef enum DXGI_FORMAT;
 #endif
 
 //-----------------------------------------------------------------------------
diff --git a/public/datacache/imdlcache.h b/public/datacache/imdlcache.h
index cd805335..7eccfff1 100644
--- a/public/datacache/imdlcache.h
+++ b/public/datacache/imdlcache.h
@@ -43,7 +43,7 @@ typedef unsigned short MDLHandle_t;
 
 inline MDLHandle_t VoidPtrToMDLHandle( void *ptr )
 {
-	return (MDLHandle_t)(int)ptr;
+	return (MDLHandle_t)(uintp)ptr;
 }
 
 enum
diff --git a/public/mathlib/ssemath.h b/public/mathlib/ssemath.h
index d24cd643..efcfdddb 100644
--- a/public/mathlib/ssemath.h
+++ b/public/mathlib/ssemath.h
@@ -2931,6 +2931,12 @@ FORCEINLINE i32x4 IntShiftLeftWordSIMD(const i32x4 &vSrcA, const i32x4 &vSrcB)
 // like this.
 FORCEINLINE void ConvertStoreAsIntsSIMD(intx4 * RESTRICT pDest, const fltx4 &vSrc)
 {
+#ifdef COMPILER_MSVC64
+	(*pDest)[0] = SubFloat(vSrc, 0);
+	(*pDest)[1] = SubFloat(vSrc, 1);
+	(*pDest)[2] = SubFloat(vSrc, 2);
+	(*pDest)[3] = SubFloat(vSrc, 3);
+#else
 	__m64 bottom = _mm_cvttps_pi32( vSrc );
 	__m64 top    = _mm_cvttps_pi32( _mm_movehl_ps(vSrc,vSrc) );
 
@@ -2938,6 +2944,7 @@ FORCEINLINE void ConvertStoreAsIntsSIMD(intx4 * RESTRICT pDest, const fltx4 &vSr
 	*reinterpret_cast<__m64 *>(&(*pDest)[2]) = top;
 
 	_mm_empty();
+#endif
 }
 
 
diff --git a/public/steam/steamtypes.h b/public/steam/steamtypes.h
index 44a20e61..e95147f9 100644
--- a/public/steam/steamtypes.h
+++ b/public/steam/steamtypes.h
@@ -22,7 +22,7 @@ typedef unsigned char uint8;
 	#define POSIX 1
 #endif
 
-#if defined(__x86_64__) || defined(_WIN64)
+#if (defined(__x86_64__) || defined(_WIN64)) && !defined(X64BITS) 
 #define X64BITS
 #endif
 
diff --git a/public/tier1/bitbuf.h b/public/tier1/bitbuf.h
index ad8c9dad..19b07ae3 100644
--- a/public/tier1/bitbuf.h
+++ b/public/tier1/bitbuf.h
@@ -1123,7 +1123,7 @@ FORCEINLINE void CBitRead::GrabNextDWord( bool bOverFlowImmediately )
 		}
 		else
 		{
-			Assert( reinterpret_cast<int>(m_pDataIn) + 3 < reinterpret_cast<int>(m_pBufferEnd));
+			Assert( reinterpret_cast<uintp>(m_pDataIn) + 3 < reinterpret_cast<uintp>(m_pBufferEnd));
 			m_nInBufWord = LittleDWord( *( m_pDataIn++ ) );
 		}
 }
diff --git a/tier1/KeyValues.cpp b/tier1/KeyValues.cpp
index 450d1279..c433c649 100644
--- a/tier1/KeyValues.cpp
+++ b/tier1/KeyValues.cpp
@@ -2228,7 +2228,7 @@ bool KeyValues::WriteAsBinary( CUtlBuffer &buffer )
 			}
 		case TYPE_PTR:
 			{
-				buffer.PutUnsignedInt( (int)dat->m_pValue );
+				buffer.PutPtr( dat->m_pValue );
 			}
 
 		default:
@@ -2323,7 +2323,7 @@ bool KeyValues::ReadAsBinary( CUtlBuffer &buffer )
 			}
 		case TYPE_PTR:
 			{
-				dat->m_pValue = (void*)buffer.GetUnsignedInt();
+				dat->m_pValue = buffer.GetPtr();
 			}
 
 		default:
diff --git a/tier1/bitbuf.cpp b/tier1/bitbuf.cpp
index 5279692d..ca77bac4 100644
--- a/tier1/bitbuf.cpp
+++ b/tier1/bitbuf.cpp
@@ -331,7 +331,7 @@ bool bf_write::WriteBits(const void *pInData, int nBits)
 	}
 
 	// Align output to dword boundary
-	while (((unsigned long)pOut & 3) != 0 && nBitsLeft >= 8)
+	while (((uintp)pOut & 3) != 0 && nBitsLeft >= 8)
 	{
 
 		WriteUBitLong( *pOut, 8, false );
@@ -808,7 +808,7 @@ void old_bf_read::ReadBits(void *pOutData, int nBits)
 
 	
 	// align output to dword boundary
-	while( ((unsigned long)pOut & 3) != 0 && nBitsLeft >= 8 )
+	while( ((uintp)pOut & 3) != 0 && nBitsLeft >= 8 )
 	{
 		*pOut = (unsigned char)ReadUBitLong(8);
 		++pOut;
diff --git a/tier1/checksum_crc.cpp b/tier1/checksum_crc.cpp
index 3e0f20d4..6b907ee3 100644
--- a/tier1/checksum_crc.cpp
+++ b/tier1/checksum_crc.cpp
@@ -147,7 +147,7 @@ JustAfew:
     // The low-order two bits of pb and nBuffer in total control the
     // upfront work.
     //
-    nFront = ((unsigned int)pb) & 3;
+    nFront = ((uintp)pb) & 3;
     nBuffer -= nFront;
     switch (nFront)
     {
diff --git a/tier1/interface.cpp b/tier1/interface.cpp
index dbad03a6..f750efb6 100644
--- a/tier1/interface.cpp
+++ b/tier1/interface.cpp
@@ -154,7 +154,7 @@ static HMODULE InternalLoadLibrary( const char *pName )
 	return LoadLibraryEx( pName, NULL, LOAD_WITH_ALTERED_SEARCH_PATH );
 #endif
 }
-unsigned ThreadedLoadLibraryFunc( void *pParam )
+uintp ThreadedLoadLibraryFunc( void *pParam )
 {
 	ThreadedLoadLibaryContext_t *pContext = (ThreadedLoadLibaryContext_t*)pParam;
 	pContext->m_hLibrary = InternalLoadLibrary(pContext->m_pLibraryName);
diff --git a/tier1/newbitbuf.cpp b/tier1/newbitbuf.cpp
index 39cfd217..8bd9d1b0 100644
--- a/tier1/newbitbuf.cpp
+++ b/tier1/newbitbuf.cpp
@@ -483,7 +483,7 @@ void CBitRead::ReadBits(void *pOutData, int nBits)
 
 	
 	// align output to dword boundary
-	while( ((unsigned long)pOut & 3) != 0 && nBitsLeft >= 8 )
+	while( ((uintp)pOut & 3) != 0 && nBitsLeft >= 8 )
 	{
 		*pOut = (unsigned char)ReadUBitLong(8);
 		++pOut;
diff --git a/tier1/processor_detect.cpp b/tier1/processor_detect.cpp
index a6bfe91b..8c5a9579 100644
--- a/tier1/processor_detect.cpp
+++ b/tier1/processor_detect.cpp
@@ -10,7 +10,7 @@
 
 #include "processor_detect_linux.cpp"
 
-#elif defined( _X360 )
+#elif defined( _X360 ) || defined( WIN64 )
 
 bool CheckMMXTechnology(void) { return false; }
 bool CheckSSETechnology(void) { return false; }