diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 6977112b..779ebc77 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -1,12 +1,6 @@
 name: Build
 
-on:
-  push:
-    branches:
-      - "*"
-  pull_request:
-    branches:
-      - "*"
+on: [push, pull_request]
 
 jobs:
   build-linux-i386:
@@ -47,6 +41,17 @@ jobs:
         ./waf.bat configure -T debug
         ./waf.bat build
 
+  build-windows-amd64:
+    runs-on: windows-2019
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Build windows-amd64
+      run: |
+        git submodule init && git submodule update
+        ./waf.bat configure -T debug -8
+        ./waf.bat build
+
   build-dedicated-windows-i386:
     runs-on: windows-2019
 
@@ -58,6 +63,17 @@ jobs:
         ./waf.bat configure -T debug -d
         ./waf.bat build
 
+  build-dedicated-windows-amd64:
+    runs-on: windows-2019
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Build dedicated windows-amd64
+      run: |
+        git submodule init && git submodule update
+        ./waf.bat configure -T debug -d -8
+        ./waf.bat build
+
   build-dedicated-linux-i386:
     runs-on: ubuntu-18.04
 
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index a0742c16..4974855e 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -1,12 +1,6 @@
 name: Tests
 
-on:
-  push:
-    branches:
-      - "*"
-  pull_request:
-    branches:
-      - "*"
+on: [push, pull_request]
 
 jobs:
   tests-linux-i386:
@@ -40,3 +34,17 @@ jobs:
         cd out
         $env:Path = "bin";
         ./unittest.exe
+
+  tests-windows-amd64:
+    runs-on: windows-2019
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Run tests windows-amd64
+      run: |
+        git submodule init && git submodule update
+        ./waf.bat configure -T release --tests --prefix=out/ -8
+        ./waf.bat install
+        cd out
+        $env:Path = "bin";
+        ./unittest.exe
diff --git a/dedicated/sys_ded.cpp b/dedicated/sys_ded.cpp
index c7a9be92..f1ff4449 100644
--- a/dedicated/sys_ded.cpp
+++ b/dedicated/sys_ded.cpp
@@ -470,7 +470,7 @@ bool CDedicatedSteamApplication::Create( )
 //-----------------------------------------------------------------------------
 int main(int argc, char **argv)
 {
-#ifndef POSIX
+#if !defined( POSIX ) && !defined( PLATFORM_64BITS )
 	_asm
 	{
 		fninit
diff --git a/engine/downloadthread.cpp b/engine/downloadthread.cpp
index a79ebff5..882609f7 100644
--- a/engine/downloadthread.cpp
+++ b/engine/downloadthread.cpp
@@ -425,7 +425,7 @@ DWORD __stdcall DownloadThread( void *voidPtr )
 		//Thread_DPrintf( "Requesting full download\n%s", headers );
 	}
 
-	rc.hDataResource = InternetOpenUrl(rc.hOpenResource, fullURL, headerPtr, headerLen, flags,(DWORD)(&rc) );
+	rc.hDataResource = InternetOpenUrl(rc.hOpenResource, fullURL, headerPtr, headerLen, flags, (DWORD_PTR)(&rc) );
 
 	// send the request off
 	if ( !rc.hDataResource )
diff --git a/engine/tmessage.cpp b/engine/tmessage.cpp
index 72c65f22..c5e00116 100644
--- a/engine/tmessage.cpp
+++ b/engine/tmessage.cpp
@@ -322,10 +322,17 @@ int ParseDirective( const char *pText )
 		{
 			if ( ParseFloats( pText, tempFloat, 4 ) )
 			{
-				for ( int i = 0; i < 4; ++i )
+				// that's original code, msvc2015 generates illegal instruction on amd64 architecture
+				/*for ( int i = 0; i < 4; ++i )
 				{
 					gMessageParms.boxcolor[ i ] = (byte)(int)tempFloat[ i ];
-				}
+				}*/
+
+				// workaround
+				gMessageParms.boxcolor[0] = (int)tempFloat[0];
+				gMessageParms.boxcolor[1] = (int)tempFloat[1];
+				gMessageParms.boxcolor[2] = (int)tempFloat[2];
+				gMessageParms.boxcolor[3] = (int)tempFloat[3];
 			}
 		}
 		else if ( IsToken( pText, "clearmessage" ) )
diff --git a/filesystem/filesystem_stdio.cpp b/filesystem/filesystem_stdio.cpp
index f80d4e4a..29caa925 100644
--- a/filesystem/filesystem_stdio.cpp
+++ b/filesystem/filesystem_stdio.cpp
@@ -1413,7 +1413,7 @@ size_t CWin32ReadOnlyFile::FS_fread( void *dest, size_t destSize, size_t size )
 	if ( m_hFileUnbuffered != INVALID_HANDLE_VALUE )
 	{
 		const int destBaseAlign = ( IsX360() ) ? 4 : m_SectorSize;
-		bool bDestBaseIsAligned = ( (DWORD)dest % destBaseAlign == 0 );
+		bool bDestBaseIsAligned = ( (DWORD_PTR)dest % destBaseAlign == 0 );
 		bool bCanReadUnbufferedDirect = ( bDestBaseIsAligned && ( destSize % m_SectorSize == 0 ) && ( m_ReadPos % m_SectorSize == 0 ) );
 
 		if ( bCanReadUnbufferedDirect )
diff --git a/game/client/client_thinklist.cpp b/game/client/client_thinklist.cpp
index eae2d880..bbb70a7b 100644
--- a/game/client/client_thinklist.cpp
+++ b/game/client/client_thinklist.cpp
@@ -158,7 +158,7 @@ void CClientThinkList::RemoveThinkable( ClientThinkHandle_t hThink )
 	{
 		pThink->SetThinkHandle( INVALID_THINK_HANDLE );
 	}
-	m_ThinkEntries.Remove( (unsigned long)hThink );
+	m_ThinkEntries.Remove( (uintp)hThink );
 }
 
 
@@ -304,7 +304,7 @@ void CClientThinkList::PerformThinkFunctions()
 		if ( hThink != INVALID_THINK_HANDLE )
 		{
 			// This can happen if the same think handle was removed twice
-			if ( !m_ThinkEntries.IsInList( (unsigned long)hThink ) )
+			if ( !m_ThinkEntries.IsInList( (uintp)hThink ) )
 				continue;
 
 			// NOTE: This is necessary for the case where the client entity handle
diff --git a/game/client/client_thinklist.h b/game/client/client_thinklist.h
index 3d3e1744..9d3b3b54 100644
--- a/game/client/client_thinklist.h
+++ b/game/client/client_thinklist.h
@@ -121,7 +121,7 @@ inline ClientThinkHandle_t CClientThinkList::GetInvalidThinkHandle()
 
 inline CClientThinkList::ThinkEntry_t* CClientThinkList::GetThinkEntry( ClientThinkHandle_t hThink )
 {
-	return &m_ThinkEntries[ (unsigned long)hThink ];
+	return &m_ThinkEntries[ (uintp)hThink ];
 }
 
 
diff --git a/game/client/clientleafsystem.cpp b/game/client/clientleafsystem.cpp
index f8e46d88..c00481fd 100644
--- a/game/client/clientleafsystem.cpp
+++ b/game/client/clientleafsystem.cpp
@@ -1337,7 +1337,7 @@ void CClientLeafSystem::ComputeTranslucentRenderLeaf( int count, const LeafIndex
 
 	static CUtlVector<RenderableInfo_t *> orderedList; // @MULTICORE (toml 8/30/2006): will need to make non-static if thread this function
 	static CUtlVector<IClientRenderable *> renderablesToUpdate;
-	int leaf = 0;
+	intp leaf = 0;
 	for ( i = 0; i < count; ++i )
 	{
 		leaf = pLeafList[i];
diff --git a/game/server/ai_navigator.cpp b/game/server/ai_navigator.cpp
index 2825744c..c304bcdc 100644
--- a/game/server/ai_navigator.cpp
+++ b/game/server/ai_navigator.cpp
@@ -1222,7 +1222,7 @@ float CAI_Navigator::GetPathTimeToGoal()
 AI_PathNode_t CAI_Navigator::GetNearestNode()
 {
 #ifdef WIN32
-	COMPILE_TIME_ASSERT( (int)AIN_NO_NODE == NO_NODE );
+	COMPILE_TIME_ASSERT( (intp)AIN_NO_NODE == NO_NODE );
 #endif
 	return (AI_PathNode_t)(intp)( GetPathfinder()->NearestNodeToNPC() );
 }
diff --git a/ivp b/ivp
index dfa42eb5..960c7228 160000
--- a/ivp
+++ b/ivp
@@ -1 +1 @@
-Subproject commit dfa42eb575618661a9c41c2ed635c1b9a0a51858
+Subproject commit 960c7228f8e8d710625891991e88b1ec3aa92e45
diff --git a/materialsystem/CColorCorrection.cpp b/materialsystem/CColorCorrection.cpp
index 5483d18e..46246658 100644
--- a/materialsystem/CColorCorrection.cpp
+++ b/materialsystem/CColorCorrection.cpp
@@ -79,7 +79,7 @@ ColorCorrectionLookup_t::~ColorCorrectionLookup_t( )
 void ColorCorrectionLookup_t::AllocTexture()
 {
 	char name[64];
-	sprintf( name, "ColorCorrection - %d", m_Handle );
+	sprintf( name, "ColorCorrection - %p", m_Handle );
 
 	m_pColorCorrectionTexture = ITextureInternal::CreateProceduralTexture( name, TEXTURE_GROUP_OTHER,
 		COLOR_CORRECTION_TEXTURE_SIZE, COLOR_CORRECTION_TEXTURE_SIZE, COLOR_CORRECTION_TEXTURE_SIZE, IMAGE_FORMAT_BGRX8888,
diff --git a/public/basehandle.h b/public/basehandle.h
index 91eb02d0..0e35ddb3 100644
--- a/public/basehandle.h
+++ b/public/basehandle.h
@@ -30,7 +30,7 @@ public:
 
 	CBaseHandle();
 	CBaseHandle( const CBaseHandle &other );
-	CBaseHandle( unsigned long value );
+	CBaseHandle( uintp value );
 	CBaseHandle( int iEntry, int iSerialNumber );
 
 	void Init( int iEntry, int iSerialNumber );
@@ -63,7 +63,7 @@ public:
 protected:
 	// The low NUM_SERIAL_BITS hold the index. If this value is less than MAX_EDICTS, then the entity is networkable.
 	// The high NUM_SERIAL_NUM_BITS bits are the serial number.
-	unsigned long	m_Index;
+	uintp	m_Index;
 };
 
 
@@ -80,7 +80,7 @@ inline CBaseHandle::CBaseHandle( const CBaseHandle &other )
 	m_Index = other.m_Index;
 }
 
-inline CBaseHandle::CBaseHandle( unsigned long value )
+inline CBaseHandle::CBaseHandle( uintp value )
 {
 	m_Index = value;
 }
@@ -150,7 +150,7 @@ inline bool CBaseHandle::operator <( const CBaseHandle &other ) const
 
 inline bool CBaseHandle::operator <( const IHandleEntity *pEntity ) const
 {
-	unsigned long otherIndex = (pEntity) ? pEntity->GetRefEHandle().m_Index : INVALID_EHANDLE_INDEX;
+	uintp otherIndex = (pEntity) ? pEntity->GetRefEHandle().m_Index : INVALID_EHANDLE_INDEX;
 	return m_Index < otherIndex;
 }
 
diff --git a/public/saverestoretypes.h b/public/saverestoretypes.h
index 4bfb25b4..e470f662 100644
--- a/public/saverestoretypes.h
+++ b/public/saverestoretypes.h
@@ -102,7 +102,7 @@ struct levellist_t
 
 struct EHandlePlaceholder_t // Engine does some of the game writing (alas, probably shouldn't), but can't see ehandle.h
 {
-	unsigned long i;
+	uintp i;
 };
 
 //-------------------------------------
diff --git a/studiorender/r_studiodraw.cpp b/studiorender/r_studiodraw.cpp
index da6905fd..c2aee1fb 100644
--- a/studiorender/r_studiodraw.cpp
+++ b/studiorender/r_studiodraw.cpp
@@ -1138,7 +1138,7 @@ public:
 		if ( nHasSIMD )
 		{
 			// Precaches the data
-			_mm_prefetch( (char*)((int)pGroupToMesh & (~0x1F)), _MM_HINT_NTA );
+			_mm_prefetch( (char*)((intp)pGroupToMesh & (~0x1F)), _MM_HINT_NTA );
 		}
 #endif
 		for ( int i = 0; i < PREFETCH_VERT_COUNT; ++i )
@@ -1165,7 +1165,7 @@ public:
 			if ( nHasSIMD )
 			{
 				char *pMem = (char*)&pGroupToMesh[j + PREFETCH_VERT_COUNT + 1];
-				_mm_prefetch( (char*)((int)pMem & (~0x1F)), _MM_HINT_NTA );
+				_mm_prefetch( (char*)((intp)pMem & (~0x1F)), _MM_HINT_NTA );
 			}
 #endif
 			idx = j & (PREFETCH_VERT_COUNT-1);
diff --git a/wscript b/wscript
index 5c12bf40..c2f86949 100644
--- a/wscript
+++ b/wscript
@@ -394,7 +394,8 @@ def configure(conf):
 			'/Zc:forScope',
 			'/Zc:wchar_t',
 			'/GR',
-			'/TP'
+			'/TP',
+			'/EHsc'
 		]
 		
 		if conf.options.BUILD_TYPE == 'debug':