diff --git a/build/premake/premake.lua b/build/premake/premake.lua
index e9acd5dd8c..88423801b8 100755
--- a/build/premake/premake.lua
+++ b/build/premake/premake.lua
@@ -8,6 +8,18 @@ addoption("without-pch", "Disable generation and usage of precompiled headers")
 dofile("functions.lua")
 dofile("extern_libs.lua")
 
+-- detect CPU architecture (simplistic, currently only supports x86 and amd64
+arch = "x86"
+if OS == "windows" then
+	if os.getenv("PROCESSOR_ARCHITECTURE") == "amd64" or os.getenv("PROCESSOR_ARCHITEW6432") == "amd64" then
+		arch = "amd64"
+	end
+else
+	if os.getenv("HOSTTYPE") == "x86_64" then
+		arch = "amd64"
+	end
+end
+
 -- Set up the Project
 project.name = "pyrogenesis"
 project.bindir   = "../../binaries/system"
@@ -432,13 +444,22 @@ function setup_all_libs ()
 		"valgrind"
 	}
 
+	-- CPU architecture-specific
+	if arch == "amd64" then
+		tinsert(source_dirs, "lib/sysdep/arch/amd64");
+		tinsert(source_dirs, "lib/sysdep/arch/x86_x64");
+	else
+		tinsert(source_dirs, "lib/sysdep/arch/ia32");
+		tinsert(source_dirs, "lib/sysdep/arch/x86_x64");
+	end
+	
 	-- OS-specific
 	sysdep_dirs = {
-		linux = { "lib/sysdep/linux", "lib/sysdep/unix", "lib/sysdep/unix/x" },
+		linux = { "lib/sysdep/os/linux", "lib/sysdep/os/unix", "lib/sysdep/os/unix/x" },
 		-- note: RC file must be added to main_exe package.
 		-- note: don't add "lib/sysdep/win/aken.cpp" because that must be compiled with the DDK.
-		windows = { "lib/sysdep/win", "lib/sysdep/win/wposix", "lib/sysdep/win/whrt" },
-		macosx = { "lib/sysdep/osx", "lib/sysdep/unix" },
+		windows = { "lib/sysdep/os/win", "lib/sysdep/os/win/wposix", "lib/sysdep/os/win/whrt" },
+		macosx = { "lib/sysdep/os/osx", "lib/sysdep/os/unix" },
 	}
 	for i,v in sysdep_dirs[OS] do
 		tinsert(source_dirs, v);
diff --git a/source/graphics/Color.cpp b/source/graphics/Color.cpp
index 09e0d0dbf1..6ac6334659 100644
--- a/source/graphics/Color.cpp
+++ b/source/graphics/Color.cpp
@@ -12,7 +12,7 @@
 
 #include "maths/MathUtil.h"
 #include "graphics/SColor.h"
-#include "lib/sysdep/x86_x64/x86_x64.h"
+#include "lib/sysdep/arch/x86_x64/x86_x64.h"
 
 static u32 fallback_ConvertRGBColorTo4ub(const RGBColor& src)
 {
diff --git a/source/graphics/Color_asm.asm b/source/graphics/Color_asm.asm
index c094498ca6..754ef06c48 100644
--- a/source/graphics/Color_asm.asm
+++ b/source/graphics/Color_asm.asm
@@ -1,4 +1,4 @@
-%include "../lib/sysdep/ia32/ia32.inc"
+%include "../lib/sysdep/arch/ia32/ia32.inc"
 
 ;-------------------------------------------------------------------------------
 ; Color conversion (SSE)
diff --git a/source/lib/allocators/aligned_allocator.h b/source/lib/allocators/aligned_allocator.h
index 4d0b9f91c2..2f81882a69 100644
--- a/source/lib/allocators/aligned_allocator.h
+++ b/source/lib/allocators/aligned_allocator.h
@@ -12,7 +12,7 @@
 #define ALIGNED_ALLOCATOR
 
 #include "lib/bits.h"	// round_up
-#include "lib/sysdep/x86_x64/x86_x64.h"	// x86_x64_L1CacheLineSize
+#include "lib/sysdep/arch/x86_x64/x86_x64.h"	// x86_x64_L1CacheLineSize
 #include "lib/sysdep/rtl.h"	// rtl_AllocateAligned
 
 
diff --git a/source/lib/debug.cpp b/source/lib/debug.cpp
index d2d649dd88..475ce28d58 100644
--- a/source/lib/debug.cpp
+++ b/source/lib/debug.cpp
@@ -23,7 +23,7 @@
 #include "lib/sysdep/sysdep.h"
 
 #if OS_WIN
-#include "lib/sysdep/win/wdbg_heap.h"
+#include "lib/sysdep/os/win/wdbg_heap.h"
 #endif
 
 
diff --git a/source/lib/external_libraries/sdl.h b/source/lib/external_libraries/sdl.h
index 38491c3e34..7d7cdce5ef 100644
--- a/source/lib/external_libraries/sdl.h
+++ b/source/lib/external_libraries/sdl.h
@@ -15,7 +15,7 @@
 #include "lib/config2.h"	// CONFIG2_WSDL
 
 #if OS_WIN && CONFIG2_WSDL
-# include "lib/sysdep/win/wsdl.h"
+# include "lib/sysdep/os/win/wsdl.h"
 #else
 
 # include <SDL/SDL.h>
diff --git a/source/lib/ogl.h b/source/lib/ogl.h
index e9f41b64f3..243dd125b5 100644
--- a/source/lib/ogl.h
+++ b/source/lib/ogl.h
@@ -15,7 +15,7 @@
 // wgl.h is a private header and should only be included from here.
 // if this isn't defined, it'll complain.
 #define WGL_HEADER_NEEDED
-#include "lib/sysdep/win/wgl.h"
+#include "lib/sysdep/os/win/wgl.h"
 #endif
 
 
diff --git a/source/lib/posix/posix.cpp b/source/lib/posix/posix.cpp
index 2e56098882..75d9e92baa 100644
--- a/source/lib/posix/posix.cpp
+++ b/source/lib/posix/posix.cpp
@@ -2,7 +2,7 @@
 #include "posix.h"
 
 #if ARCH_IA32
-# include "lib/sysdep/ia32/ia32_asm.h"
+# include "lib/sysdep/arch/ia32/ia32_asm.h"
 #endif
 
 
diff --git a/source/lib/posix/posix.h b/source/lib/posix/posix.h
index f0bcadb042..d31d8c0fd1 100644
--- a/source/lib/posix/posix.h
+++ b/source/lib/posix/posix.h
@@ -47,7 +47,7 @@ need only be renamed (e.g. _open, _stat).
 #include <cmath>	// see isfinite comment below
 
 #if OS_WIN
-# include "lib/sysdep/win/wposix/wposix.h"
+# include "lib/sysdep/os/win/wposix/wposix.h"
 #endif
 
 #include "posix_types.h"
diff --git a/source/lib/posix/posix_aio.h b/source/lib/posix/posix_aio.h
index f536ee4e79..2cb9e38aa3 100644
--- a/source/lib/posix/posix_aio.h
+++ b/source/lib/posix/posix_aio.h
@@ -4,7 +4,7 @@
 #include <fcntl.h>
 
 #if OS_WIN
-# include "lib/sysdep/win/wposix/waio.h"
+# include "lib/sysdep/os/win/wposix/waio.h"
 #else
 # include <aio.h>
 #endif
diff --git a/source/lib/posix/posix_dlfcn.h b/source/lib/posix/posix_dlfcn.h
index a38ecff049..f56952c4f7 100644
--- a/source/lib/posix/posix_dlfcn.h
+++ b/source/lib/posix/posix_dlfcn.h
@@ -1,5 +1,5 @@
 #if OS_WIN
-# include "lib/sysdep/win/wposix/wdlfcn.h"
+# include "lib/sysdep/os/win/wposix/wdlfcn.h"
 #else
 # include <dlfcn.h>
 #endif
diff --git a/source/lib/posix/posix_errno.h b/source/lib/posix/posix_errno.h
index 6d69359ec8..c70b0ec0a9 100644
--- a/source/lib/posix/posix_errno.h
+++ b/source/lib/posix/posix_errno.h
@@ -1,5 +1,5 @@
 #if OS_WIN
-# include "lib/sysdep/win/wposix/werrno.h"
+# include "lib/sysdep/os/win/wposix/werrno.h"
 #else
 # include <errno.h>
 #endif
diff --git a/source/lib/posix/posix_filesystem.h b/source/lib/posix/posix_filesystem.h
index 420effb847..f7b702b394 100644
--- a/source/lib/posix/posix_filesystem.h
+++ b/source/lib/posix/posix_filesystem.h
@@ -1,5 +1,5 @@
 #if OS_WIN
-# include "lib/sysdep/win/wposix/wfilesystem.h"
+# include "lib/sysdep/os/win/wposix/wfilesystem.h"
 #else
 # include <sys/stat.h>
 # include <sys/types.h>
diff --git a/source/lib/posix/posix_mman.h b/source/lib/posix/posix_mman.h
index b2e24af1bc..6183f0eb16 100644
--- a/source/lib/posix/posix_mman.h
+++ b/source/lib/posix/posix_mman.h
@@ -1,5 +1,5 @@
 #if OS_WIN
-# include "lib/sysdep/win/wposix/wmman.h"
+# include "lib/sysdep/os/win/wposix/wmman.h"
 #else
 # include <sys/mman.h>
 #endif
diff --git a/source/lib/posix/posix_pthread.h b/source/lib/posix/posix_pthread.h
index 9e6ee6b739..f7e95b4013 100644
--- a/source/lib/posix/posix_pthread.h
+++ b/source/lib/posix/posix_pthread.h
@@ -1,5 +1,5 @@
 #if OS_WIN
-# include "lib/sysdep/win/wposix/wpthread.h"
+# include "lib/sysdep/os/win/wposix/wpthread.h"
 #else
 # include <pthread.h>
 # include <semaphore.h>
diff --git a/source/lib/posix/posix_sock.h b/source/lib/posix/posix_sock.h
index ccebe8d5d5..21b2ee3ea8 100644
--- a/source/lib/posix/posix_sock.h
+++ b/source/lib/posix/posix_sock.h
@@ -1,5 +1,5 @@
 #if OS_WIN
-# include "lib/sysdep/win/wposix/wsock.h"
+# include "lib/sysdep/os/win/wposix/wsock.h"
 #else
 # include <sys/socket.h>
 # include <netdb.h>
diff --git a/source/lib/posix/posix_terminal.h b/source/lib/posix/posix_terminal.h
index 2bc6432c12..7cb45ff8e9 100644
--- a/source/lib/posix/posix_terminal.h
+++ b/source/lib/posix/posix_terminal.h
@@ -1,5 +1,5 @@
 #if OS_WIN
-# include "lib/sysdep/win/wposix/wterminal.h"
+# include "lib/sysdep/os/win/wposix/wterminal.h"
 #else
 # include <sys/ioctl.h>
 #endif
diff --git a/source/lib/posix/posix_time.h b/source/lib/posix/posix_time.h
index 2e196c2715..a9190b93a7 100644
--- a/source/lib/posix/posix_time.h
+++ b/source/lib/posix/posix_time.h
@@ -1,5 +1,5 @@
 #if OS_WIN
-# include "lib/sysdep/win/wposix/wtime.h"
+# include "lib/sysdep/os/win/wposix/wtime.h"
 #else
 # include <sys/time.h>
 #endif
diff --git a/source/lib/posix/posix_types.h b/source/lib/posix/posix_types.h
index db20cde614..4e8a90f3ba 100644
--- a/source/lib/posix/posix_types.h
+++ b/source/lib/posix/posix_types.h
@@ -19,7 +19,7 @@
 #include <limits.h>
 
 #if OS_WIN
-# include "lib/sysdep/win/wposix/wposix_types.h"
+# include "lib/sysdep/os/win/wposix/wposix_types.h"
 #else
 
 // unix/linux/glibc/gcc says that this macro has to be defined when including
diff --git a/source/lib/posix/posix_utsname.h b/source/lib/posix/posix_utsname.h
index 1089e8ab4a..678cc14e16 100644
--- a/source/lib/posix/posix_utsname.h
+++ b/source/lib/posix/posix_utsname.h
@@ -1,5 +1,5 @@
 #if OS_WIN
-# include "lib/sysdep/win/wposix/wutsname.h"
+# include "lib/sysdep/os/win/wposix/wutsname.h"
 #else
 # include <sys/utsname.h>
 #endif
diff --git a/source/lib/res/sound/snd_mgr.cpp b/source/lib/res/sound/snd_mgr.cpp
index 63248a0aa9..c1e090ba78 100644
--- a/source/lib/res/sound/snd_mgr.cpp
+++ b/source/lib/res/sound/snd_mgr.cpp
@@ -27,7 +27,7 @@ extern PIVFS g_VFS;
 
 // for DLL-load hack in alc_init
 #if OS_WIN
-# include "lib/sysdep/win/win.h"
+# include "lib/sysdep/os/win/win.h"
 #endif
 
 #include "lib/timer.h"
diff --git a/source/lib/sysdep/acpi.cpp b/source/lib/sysdep/acpi.cpp
index e9d0d8a918..957068b1f2 100644
--- a/source/lib/sysdep/acpi.cpp
+++ b/source/lib/sysdep/acpi.cpp
@@ -1,7 +1,7 @@
 #include "precompiled.h"
 #include "acpi.h"
 
-#include "win/mahaf.h"
+#include "lib/sysdep/os/win/mahaf.h"
 #include "lib/sysdep/cpu.h"
 #include "lib/module_init.h"
 
diff --git a/source/lib/sysdep/amd64/amd64.cpp b/source/lib/sysdep/arch/amd64/amd64.cpp
similarity index 100%
rename from source/lib/sysdep/amd64/amd64.cpp
rename to source/lib/sysdep/arch/amd64/amd64.cpp
diff --git a/source/lib/sysdep/amd64/amd64.h b/source/lib/sysdep/arch/amd64/amd64.h
similarity index 100%
rename from source/lib/sysdep/amd64/amd64.h
rename to source/lib/sysdep/arch/amd64/amd64.h
diff --git a/source/lib/sysdep/amd64/amd64_abi.inc b/source/lib/sysdep/arch/amd64/amd64_abi.inc
similarity index 100%
rename from source/lib/sysdep/amd64/amd64_abi.inc
rename to source/lib/sysdep/arch/amd64/amd64_abi.inc
diff --git a/source/lib/sysdep/amd64/amd64_asm.asm b/source/lib/sysdep/arch/amd64/amd64_asm.asm
similarity index 100%
rename from source/lib/sysdep/amd64/amd64_asm.asm
rename to source/lib/sysdep/arch/amd64/amd64_asm.asm
diff --git a/source/lib/sysdep/amd64/amd64_asm.h b/source/lib/sysdep/arch/amd64/amd64_asm.h
similarity index 100%
rename from source/lib/sysdep/amd64/amd64_asm.h
rename to source/lib/sysdep/arch/amd64/amd64_asm.h
diff --git a/source/lib/sysdep/ia32/ia32.cpp b/source/lib/sysdep/arch/ia32/ia32.cpp
similarity index 100%
rename from source/lib/sysdep/ia32/ia32.cpp
rename to source/lib/sysdep/arch/ia32/ia32.cpp
diff --git a/source/lib/sysdep/ia32/ia32.h b/source/lib/sysdep/arch/ia32/ia32.h
similarity index 100%
rename from source/lib/sysdep/ia32/ia32.h
rename to source/lib/sysdep/arch/ia32/ia32.h
diff --git a/source/lib/sysdep/ia32/ia32.inc b/source/lib/sysdep/arch/ia32/ia32.inc
similarity index 100%
rename from source/lib/sysdep/ia32/ia32.inc
rename to source/lib/sysdep/arch/ia32/ia32.inc
diff --git a/source/lib/sysdep/ia32/ia32_asm.asm b/source/lib/sysdep/arch/ia32/ia32_asm.asm
similarity index 100%
rename from source/lib/sysdep/ia32/ia32_asm.asm
rename to source/lib/sysdep/arch/ia32/ia32_asm.asm
diff --git a/source/lib/sysdep/ia32/ia32_asm.h b/source/lib/sysdep/arch/ia32/ia32_asm.h
similarity index 100%
rename from source/lib/sysdep/ia32/ia32_asm.h
rename to source/lib/sysdep/arch/ia32/ia32_asm.h
diff --git a/source/lib/sysdep/ia32/ia32_memcpy.asm b/source/lib/sysdep/arch/ia32/ia32_memcpy.asm
similarity index 100%
rename from source/lib/sysdep/ia32/ia32_memcpy.asm
rename to source/lib/sysdep/arch/ia32/ia32_memcpy.asm
diff --git a/source/lib/sysdep/ia32/ia32_memcpy.h b/source/lib/sysdep/arch/ia32/ia32_memcpy.h
similarity index 100%
rename from source/lib/sysdep/ia32/ia32_memcpy.h
rename to source/lib/sysdep/arch/ia32/ia32_memcpy.h
diff --git a/source/lib/sysdep/x86_x64/topology.cpp b/source/lib/sysdep/arch/x86_x64/topology.cpp
similarity index 100%
rename from source/lib/sysdep/x86_x64/topology.cpp
rename to source/lib/sysdep/arch/x86_x64/topology.cpp
diff --git a/source/lib/sysdep/x86_x64/topology.h b/source/lib/sysdep/arch/x86_x64/topology.h
similarity index 100%
rename from source/lib/sysdep/x86_x64/topology.h
rename to source/lib/sysdep/arch/x86_x64/topology.h
diff --git a/source/lib/sysdep/x86_x64/x86_x64.cpp b/source/lib/sysdep/arch/x86_x64/x86_x64.cpp
similarity index 100%
rename from source/lib/sysdep/x86_x64/x86_x64.cpp
rename to source/lib/sysdep/arch/x86_x64/x86_x64.cpp
diff --git a/source/lib/sysdep/x86_x64/x86_x64.h b/source/lib/sysdep/arch/x86_x64/x86_x64.h
similarity index 100%
rename from source/lib/sysdep/x86_x64/x86_x64.h
rename to source/lib/sysdep/arch/x86_x64/x86_x64.h
diff --git a/source/lib/sysdep/linux/dir_watch_fam.cpp b/source/lib/sysdep/os/linux/dir_watch_fam.cpp
similarity index 100%
rename from source/lib/sysdep/linux/dir_watch_fam.cpp
rename to source/lib/sysdep/os/linux/dir_watch_fam.cpp
diff --git a/source/lib/sysdep/linux/lcpu.cpp b/source/lib/sysdep/os/linux/lcpu.cpp
similarity index 100%
rename from source/lib/sysdep/linux/lcpu.cpp
rename to source/lib/sysdep/os/linux/lcpu.cpp
diff --git a/source/lib/sysdep/linux/ldbg.cpp b/source/lib/sysdep/os/linux/ldbg.cpp
similarity index 100%
rename from source/lib/sysdep/linux/ldbg.cpp
rename to source/lib/sysdep/os/linux/ldbg.cpp
diff --git a/source/lib/sysdep/linux/linux.cpp b/source/lib/sysdep/os/linux/linux.cpp
similarity index 100%
rename from source/lib/sysdep/linux/linux.cpp
rename to source/lib/sysdep/os/linux/linux.cpp
diff --git a/source/lib/sysdep/osx/dir_watch.cpp b/source/lib/sysdep/os/osx/dir_watch.cpp
similarity index 100%
rename from source/lib/sysdep/osx/dir_watch.cpp
rename to source/lib/sysdep/os/osx/dir_watch.cpp
diff --git a/source/lib/sysdep/osx/ocpu.cpp b/source/lib/sysdep/os/osx/ocpu.cpp
similarity index 100%
rename from source/lib/sysdep/osx/ocpu.cpp
rename to source/lib/sysdep/os/osx/ocpu.cpp
diff --git a/source/lib/sysdep/osx/odbg.cpp b/source/lib/sysdep/os/osx/odbg.cpp
similarity index 100%
rename from source/lib/sysdep/osx/odbg.cpp
rename to source/lib/sysdep/os/osx/odbg.cpp
diff --git a/source/lib/sysdep/osx/osx.cpp b/source/lib/sysdep/os/osx/osx.cpp
similarity index 100%
rename from source/lib/sysdep/osx/osx.cpp
rename to source/lib/sysdep/os/osx/osx.cpp
diff --git a/source/lib/sysdep/unix/printf.cpp b/source/lib/sysdep/os/unix/printf.cpp
similarity index 100%
rename from source/lib/sysdep/unix/printf.cpp
rename to source/lib/sysdep/os/unix/printf.cpp
diff --git a/source/lib/sysdep/unix/udbg.cpp b/source/lib/sysdep/os/unix/udbg.cpp
similarity index 100%
rename from source/lib/sysdep/unix/udbg.cpp
rename to source/lib/sysdep/os/unix/udbg.cpp
diff --git a/source/lib/sysdep/unix/udbg.h b/source/lib/sysdep/os/unix/udbg.h
similarity index 100%
rename from source/lib/sysdep/unix/udbg.h
rename to source/lib/sysdep/os/unix/udbg.h
diff --git a/source/lib/sysdep/unix/unix.cpp b/source/lib/sysdep/os/unix/unix.cpp
similarity index 100%
rename from source/lib/sysdep/unix/unix.cpp
rename to source/lib/sysdep/os/unix/unix.cpp
diff --git a/source/lib/sysdep/unix/unix.h b/source/lib/sysdep/os/unix/unix.h
similarity index 100%
rename from source/lib/sysdep/unix/unix.h
rename to source/lib/sysdep/os/unix/unix.h
diff --git a/source/lib/sysdep/unix/x/x.cpp b/source/lib/sysdep/os/unix/x/x.cpp
similarity index 100%
rename from source/lib/sysdep/unix/x/x.cpp
rename to source/lib/sysdep/os/unix/x/x.cpp
diff --git a/source/lib/sysdep/win/aken/aken.cpp b/source/lib/sysdep/os/win/aken/aken.cpp
similarity index 100%
rename from source/lib/sysdep/win/aken/aken.cpp
rename to source/lib/sysdep/os/win/aken/aken.cpp
diff --git a/source/lib/sysdep/win/aken/aken.h b/source/lib/sysdep/os/win/aken/aken.h
similarity index 100%
rename from source/lib/sysdep/win/aken/aken.h
rename to source/lib/sysdep/os/win/aken/aken.h
diff --git a/source/lib/sysdep/win/aken/makefile b/source/lib/sysdep/os/win/aken/makefile
similarity index 100%
rename from source/lib/sysdep/win/aken/makefile
rename to source/lib/sysdep/os/win/aken/makefile
diff --git a/source/lib/sysdep/win/aken/sources b/source/lib/sysdep/os/win/aken/sources
similarity index 100%
rename from source/lib/sysdep/win/aken/sources
rename to source/lib/sysdep/os/win/aken/sources
diff --git a/source/lib/sysdep/win/comctl6.manifest b/source/lib/sysdep/os/win/comctl6.manifest
similarity index 100%
rename from source/lib/sysdep/win/comctl6.manifest
rename to source/lib/sysdep/os/win/comctl6.manifest
diff --git a/source/lib/sysdep/win/error_dialog.h b/source/lib/sysdep/os/win/error_dialog.h
similarity index 100%
rename from source/lib/sysdep/win/error_dialog.h
rename to source/lib/sysdep/os/win/error_dialog.h
diff --git a/source/lib/sysdep/win/error_dialog.rc b/source/lib/sysdep/os/win/error_dialog.rc
similarity index 100%
rename from source/lib/sysdep/win/error_dialog.rc
rename to source/lib/sysdep/os/win/error_dialog.rc
diff --git a/source/lib/sysdep/win/icon.rc b/source/lib/sysdep/os/win/icon.rc
similarity index 100%
rename from source/lib/sysdep/win/icon.rc
rename to source/lib/sysdep/os/win/icon.rc
diff --git a/source/lib/sysdep/win/mahaf.cpp b/source/lib/sysdep/os/win/mahaf.cpp
similarity index 100%
rename from source/lib/sysdep/win/mahaf.cpp
rename to source/lib/sysdep/os/win/mahaf.cpp
diff --git a/source/lib/sysdep/win/mahaf.h b/source/lib/sysdep/os/win/mahaf.h
similarity index 100%
rename from source/lib/sysdep/win/mahaf.h
rename to source/lib/sysdep/os/win/mahaf.h
diff --git a/source/lib/sysdep/win/manifest.cpp b/source/lib/sysdep/os/win/manifest.cpp
similarity index 100%
rename from source/lib/sysdep/win/manifest.cpp
rename to source/lib/sysdep/os/win/manifest.cpp
diff --git a/source/lib/sysdep/win/manifest.rc b/source/lib/sysdep/os/win/manifest.rc
similarity index 100%
rename from source/lib/sysdep/win/manifest.rc
rename to source/lib/sysdep/os/win/manifest.rc
diff --git a/source/lib/sysdep/win/tests/test_ia32.h b/source/lib/sysdep/os/win/tests/test_ia32.h
similarity index 90%
rename from source/lib/sysdep/win/tests/test_ia32.h
rename to source/lib/sysdep/os/win/tests/test_ia32.h
index 3ce2be9e1a..d0dd6c842b 100644
--- a/source/lib/sysdep/win/tests/test_ia32.h
+++ b/source/lib/sysdep/os/win/tests/test_ia32.h
@@ -1,6 +1,6 @@
 #include "lib/self_test.h"
 
-#include "lib/sysdep/x86_x64/x86_x64.h"
+#include "lib/sysdep/arch/x86_x64/x86_x64.h"
 
 // note: ia32_i??_from_*, ia32_rint*, ia32_fm??f are all tested within
 // sysdep to avoid test duplication (both the ia32 versions and
diff --git a/source/lib/sysdep/win/tests/test_wdbg_sym.h b/source/lib/sysdep/os/win/tests/test_wdbg_sym.h
similarity index 95%
rename from source/lib/sysdep/win/tests/test_wdbg_sym.h
rename to source/lib/sysdep/os/win/tests/test_wdbg_sym.h
index 8a8fac2160..9ad7d7b7b9 100644
--- a/source/lib/sysdep/win/tests/test_wdbg_sym.h
+++ b/source/lib/sysdep/os/win/tests/test_wdbg_sym.h
@@ -5,10 +5,10 @@
 
 #include "lib/self_test.h"
 
-#include "lib/sysdep/win/win.h"	// HWND
+#include "lib/sysdep/os/win/win.h"	// HWND
 #include "lib/debug.h"	// no wdbg_sym interface needed
 #include "lib/sysdep/sysdep.h"
-#include "lib/sysdep/win/win.h"
+#include "lib/sysdep/os/win/win.h"
 
 #include <queue>
 #include <deque>
diff --git a/source/lib/sysdep/win/wclipboard.cpp b/source/lib/sysdep/os/win/wclipboard.cpp
similarity index 94%
rename from source/lib/sysdep/win/wclipboard.cpp
rename to source/lib/sysdep/os/win/wclipboard.cpp
index 7c7ac2438c..192b37f5c0 100644
--- a/source/lib/sysdep/win/wclipboard.cpp
+++ b/source/lib/sysdep/os/win/wclipboard.cpp
@@ -1,5 +1,5 @@
 #include "precompiled.h"
-#include "../clipboard.h"
+#include "lib/sysdep/clipboard.h"
 
 #include "win.h"
 #include "wutil.h"
diff --git a/source/lib/sysdep/win/wcpu.cpp b/source/lib/sysdep/os/win/wcpu.cpp
similarity index 100%
rename from source/lib/sysdep/win/wcpu.cpp
rename to source/lib/sysdep/os/win/wcpu.cpp
diff --git a/source/lib/sysdep/win/wcpu.h b/source/lib/sysdep/os/win/wcpu.h
similarity index 100%
rename from source/lib/sysdep/win/wcpu.h
rename to source/lib/sysdep/os/win/wcpu.h
diff --git a/source/lib/sysdep/win/wcursor.cpp b/source/lib/sysdep/os/win/wcursor.cpp
similarity index 94%
rename from source/lib/sysdep/win/wcursor.cpp
rename to source/lib/sysdep/os/win/wcursor.cpp
index 6b59c0f112..bc97d73a19 100644
--- a/source/lib/sysdep/win/wcursor.cpp
+++ b/source/lib/sysdep/os/win/wcursor.cpp
@@ -1,5 +1,5 @@
 #include "precompiled.h"
-#include "../cursor.h"
+#include "lib/sysdep/cursor.h"
 
 #include "win.h"
 #include "wutil.h"
diff --git a/source/lib/sysdep/win/wdbg.cpp b/source/lib/sysdep/os/win/wdbg.cpp
similarity index 100%
rename from source/lib/sysdep/win/wdbg.cpp
rename to source/lib/sysdep/os/win/wdbg.cpp
diff --git a/source/lib/sysdep/win/wdbg.h b/source/lib/sysdep/os/win/wdbg.h
similarity index 100%
rename from source/lib/sysdep/win/wdbg.h
rename to source/lib/sysdep/os/win/wdbg.h
diff --git a/source/lib/sysdep/win/wdbg_heap.cpp b/source/lib/sysdep/os/win/wdbg_heap.cpp
similarity index 96%
rename from source/lib/sysdep/win/wdbg_heap.cpp
rename to source/lib/sysdep/os/win/wdbg_heap.cpp
index 7bd640d646..83a3700da0 100644
--- a/source/lib/sysdep/win/wdbg_heap.cpp
+++ b/source/lib/sysdep/os/win/wdbg_heap.cpp
@@ -1,7 +1,7 @@
 #include "precompiled.h"
 #include "wdbg_heap.h"
 
-#include "lib/sysdep/win/win.h"
+#include "lib/sysdep/os/win/win.h"
 #include <crtdbg.h>
 #include <excpt.h>
 #include <dbghelp.h>
diff --git a/source/lib/sysdep/win/wdbg_heap.h b/source/lib/sysdep/os/win/wdbg_heap.h
similarity index 100%
rename from source/lib/sysdep/win/wdbg_heap.h
rename to source/lib/sysdep/os/win/wdbg_heap.h
diff --git a/source/lib/sysdep/win/wdbg_sym.cpp b/source/lib/sysdep/os/win/wdbg_sym.cpp
similarity index 99%
rename from source/lib/sysdep/win/wdbg_sym.cpp
rename to source/lib/sysdep/os/win/wdbg_sym.cpp
index 092646a8d4..3ef3b8ab8d 100644
--- a/source/lib/sysdep/win/wdbg_sym.cpp
+++ b/source/lib/sysdep/os/win/wdbg_sym.cpp
@@ -23,8 +23,8 @@
 #include "lib/os_path.h"
 #include "lib/path_util.h"
 #if ARCH_IA32
-# include "lib/sysdep/ia32/ia32.h"
-# include "lib/sysdep/ia32/ia32_asm.h"
+# include "lib/sysdep/arch/ia32/ia32.h"
+# include "lib/sysdep/arch/ia32/ia32_asm.h"
 #endif
 #include "lib/external_libraries/dbghelp.h"
 #include "winit.h"
diff --git a/source/lib/sysdep/win/wdbg_sym.h b/source/lib/sysdep/os/win/wdbg_sym.h
similarity index 100%
rename from source/lib/sysdep/win/wdbg_sym.h
rename to source/lib/sysdep/os/win/wdbg_sym.h
diff --git a/source/lib/sysdep/win/wdir_watch.cpp b/source/lib/sysdep/os/win/wdir_watch.cpp
similarity index 100%
rename from source/lib/sysdep/win/wdir_watch.cpp
rename to source/lib/sysdep/os/win/wdir_watch.cpp
diff --git a/source/lib/sysdep/win/wdll_delay_load.cpp b/source/lib/sysdep/os/win/wdll_delay_load.cpp
similarity index 100%
rename from source/lib/sysdep/win/wdll_delay_load.cpp
rename to source/lib/sysdep/os/win/wdll_delay_load.cpp
diff --git a/source/lib/sysdep/win/wdll_delay_load.h b/source/lib/sysdep/os/win/wdll_delay_load.h
similarity index 100%
rename from source/lib/sysdep/win/wdll_delay_load.h
rename to source/lib/sysdep/os/win/wdll_delay_load.h
diff --git a/source/lib/sysdep/win/wdll_ver.cpp b/source/lib/sysdep/os/win/wdll_ver.cpp
similarity index 100%
rename from source/lib/sysdep/win/wdll_ver.cpp
rename to source/lib/sysdep/os/win/wdll_ver.cpp
diff --git a/source/lib/sysdep/win/wdll_ver.h b/source/lib/sysdep/os/win/wdll_ver.h
similarity index 100%
rename from source/lib/sysdep/win/wdll_ver.h
rename to source/lib/sysdep/os/win/wdll_ver.h
diff --git a/source/lib/sysdep/win/wgfx.cpp b/source/lib/sysdep/os/win/wgfx.cpp
similarity index 100%
rename from source/lib/sysdep/win/wgfx.cpp
rename to source/lib/sysdep/os/win/wgfx.cpp
diff --git a/source/lib/sysdep/win/wgl.h b/source/lib/sysdep/os/win/wgl.h
similarity index 100%
rename from source/lib/sysdep/win/wgl.h
rename to source/lib/sysdep/os/win/wgl.h
diff --git a/source/lib/sysdep/win/whrt/counter.cpp b/source/lib/sysdep/os/win/whrt/counter.cpp
similarity index 100%
rename from source/lib/sysdep/win/whrt/counter.cpp
rename to source/lib/sysdep/os/win/whrt/counter.cpp
diff --git a/source/lib/sysdep/win/whrt/counter.h b/source/lib/sysdep/os/win/whrt/counter.h
similarity index 100%
rename from source/lib/sysdep/win/whrt/counter.h
rename to source/lib/sysdep/os/win/whrt/counter.h
diff --git a/source/lib/sysdep/win/whrt/hpet.cpp b/source/lib/sysdep/os/win/whrt/hpet.cpp
similarity index 94%
rename from source/lib/sysdep/win/whrt/hpet.cpp
rename to source/lib/sysdep/os/win/whrt/hpet.cpp
index ed3964dec3..8b01e7f6be 100644
--- a/source/lib/sysdep/win/whrt/hpet.cpp
+++ b/source/lib/sysdep/os/win/whrt/hpet.cpp
@@ -11,8 +11,8 @@
 #include "precompiled.h"
 #include "hpet.h"
 
-#include "lib/sysdep/win/win.h"
-#include "lib/sysdep/win/mahaf.h"
+#include "lib/sysdep/os/win/win.h"
+#include "lib/sysdep/os/win/mahaf.h"
 #include "lib/sysdep/acpi.h"
 #include "lib/bits.h"
 
diff --git a/source/lib/sysdep/win/whrt/hpet.h b/source/lib/sysdep/os/win/whrt/hpet.h
similarity index 100%
rename from source/lib/sysdep/win/whrt/hpet.h
rename to source/lib/sysdep/os/win/whrt/hpet.h
diff --git a/source/lib/sysdep/win/whrt/pit.h b/source/lib/sysdep/os/win/whrt/pit.h
similarity index 100%
rename from source/lib/sysdep/win/whrt/pit.h
rename to source/lib/sysdep/os/win/whrt/pit.h
diff --git a/source/lib/sysdep/win/whrt/pmt.cpp b/source/lib/sysdep/os/win/whrt/pmt.cpp
similarity index 93%
rename from source/lib/sysdep/win/whrt/pmt.cpp
rename to source/lib/sysdep/os/win/whrt/pmt.cpp
index 3c7502961d..023f1502ab 100644
--- a/source/lib/sysdep/win/whrt/pmt.cpp
+++ b/source/lib/sysdep/os/win/whrt/pmt.cpp
@@ -11,9 +11,9 @@
 #include "precompiled.h"
 #include "pmt.h"
 
-#include "lib/sysdep/win/win.h"
+#include "lib/sysdep/os/win/win.h"
 #include "lib/sysdep/acpi.h"
-#include "lib/sysdep/win/mahaf.h"
+#include "lib/sysdep/os/win/mahaf.h"
 #include "lib/bits.h"
 
 #pragma pack(push,1)
diff --git a/source/lib/sysdep/win/whrt/pmt.h b/source/lib/sysdep/os/win/whrt/pmt.h
similarity index 100%
rename from source/lib/sysdep/win/whrt/pmt.h
rename to source/lib/sysdep/os/win/whrt/pmt.h
diff --git a/source/lib/sysdep/win/whrt/qpc.cpp b/source/lib/sysdep/os/win/whrt/qpc.cpp
similarity index 95%
rename from source/lib/sysdep/win/whrt/qpc.cpp
rename to source/lib/sysdep/os/win/whrt/qpc.cpp
index 5bd012f5a3..aaa9a443ba 100644
--- a/source/lib/sysdep/win/whrt/qpc.cpp
+++ b/source/lib/sysdep/os/win/whrt/qpc.cpp
@@ -12,8 +12,8 @@
 #include "qpc.h"
 
 #include "lib/sysdep/os_cpu.h"
-#include "lib/sysdep/win/win.h"
-#include "lib/sysdep/win/wutil.h"	// wutil_argv
+#include "lib/sysdep/os/win/win.h"
+#include "lib/sysdep/os/win/wutil.h"	// wutil_argv
 #include "pit.h"	// PIT_FREQ
 #include "pmt.h"	// PMT_FREQ
 
diff --git a/source/lib/sysdep/win/whrt/qpc.h b/source/lib/sysdep/os/win/whrt/qpc.h
similarity index 100%
rename from source/lib/sysdep/win/whrt/qpc.h
rename to source/lib/sysdep/os/win/whrt/qpc.h
diff --git a/source/lib/sysdep/win/whrt/tgt.cpp b/source/lib/sysdep/os/win/whrt/tgt.cpp
similarity index 94%
rename from source/lib/sysdep/win/whrt/tgt.cpp
rename to source/lib/sysdep/os/win/whrt/tgt.cpp
index b99132869a..061760a302 100644
--- a/source/lib/sysdep/win/whrt/tgt.cpp
+++ b/source/lib/sysdep/os/win/whrt/tgt.cpp
@@ -15,7 +15,7 @@
 #include "precompiled.h"
 #include "tgt.h"
 
-#include "lib/sysdep/win/win.h"
+#include "lib/sysdep/os/win/win.h"
 #include <mmsystem.h>
 
 #if MSC_VERSION
diff --git a/source/lib/sysdep/win/whrt/tgt.h b/source/lib/sysdep/os/win/whrt/tgt.h
similarity index 100%
rename from source/lib/sysdep/win/whrt/tgt.h
rename to source/lib/sysdep/os/win/whrt/tgt.h
diff --git a/source/lib/sysdep/win/whrt/tsc.cpp b/source/lib/sysdep/os/win/whrt/tsc.cpp
similarity index 93%
rename from source/lib/sysdep/win/whrt/tsc.cpp
rename to source/lib/sysdep/os/win/whrt/tsc.cpp
index 2e93cf4ef3..3ef3d11276 100644
--- a/source/lib/sysdep/win/whrt/tsc.cpp
+++ b/source/lib/sysdep/os/win/whrt/tsc.cpp
@@ -13,12 +13,12 @@
 
 #include "lib/bits.h"
 #include "lib/sysdep/os_cpu.h"
-#include "lib/sysdep/win/win.h"
-#include "lib/sysdep/win/wutil.h"
+#include "lib/sysdep/os/win/win.h"
+#include "lib/sysdep/os/win/wutil.h"
 
 #if ARCH_IA32 || ARCH_AMD64
-# include "lib/sysdep/x86_x64/x86_x64.h"	// x86_x64_rdtsc
-# include "lib/sysdep/x86_x64/topology.h"
+# include "lib/sysdep/arch/x86_x64/x86_x64.h"	// x86_x64_rdtsc
+# include "lib/sysdep/arch/x86_x64/topology.h"
 #endif
 
 
diff --git a/source/lib/sysdep/win/whrt/tsc.h b/source/lib/sysdep/os/win/whrt/tsc.h
similarity index 100%
rename from source/lib/sysdep/win/whrt/tsc.h
rename to source/lib/sysdep/os/win/whrt/tsc.h
diff --git a/source/lib/sysdep/win/whrt/whrt.cpp b/source/lib/sysdep/os/win/whrt/whrt.cpp
similarity index 96%
rename from source/lib/sysdep/win/whrt/whrt.cpp
rename to source/lib/sysdep/os/win/whrt/whrt.cpp
index 43849a53ab..4bbd8040cf 100644
--- a/source/lib/sysdep/win/whrt/whrt.cpp
+++ b/source/lib/sysdep/os/win/whrt/whrt.cpp
@@ -14,8 +14,8 @@
 #include <process.h>	// _beginthreadex
 
 #include "lib/sysdep/cpu.h"
-#include "lib/sysdep/win/win.h"
-#include "lib/sysdep/win/winit.h"
+#include "lib/sysdep/os/win/win.h"
+#include "lib/sysdep/os/win/winit.h"
 #include "lib/sysdep/acpi.h"
 #include "lib/adts.h"
 #include "lib/bits.h"
diff --git a/source/lib/sysdep/win/whrt/whrt.h b/source/lib/sysdep/os/win/whrt/whrt.h
similarity index 100%
rename from source/lib/sysdep/win/whrt/whrt.h
rename to source/lib/sysdep/os/win/whrt/whrt.h
diff --git a/source/lib/sysdep/win/win.h b/source/lib/sysdep/os/win/win.h
similarity index 100%
rename from source/lib/sysdep/win/win.h
rename to source/lib/sysdep/os/win/win.h
diff --git a/source/lib/sysdep/win/winit.cpp b/source/lib/sysdep/os/win/winit.cpp
similarity index 100%
rename from source/lib/sysdep/win/winit.cpp
rename to source/lib/sysdep/os/win/winit.cpp
diff --git a/source/lib/sysdep/win/winit.h b/source/lib/sysdep/os/win/winit.h
similarity index 100%
rename from source/lib/sysdep/win/winit.h
rename to source/lib/sysdep/os/win/winit.h
diff --git a/source/lib/sysdep/win/wmi.cpp b/source/lib/sysdep/os/win/wmi.cpp
similarity index 100%
rename from source/lib/sysdep/win/wmi.cpp
rename to source/lib/sysdep/os/win/wmi.cpp
diff --git a/source/lib/sysdep/win/wmi.h b/source/lib/sysdep/os/win/wmi.h
similarity index 100%
rename from source/lib/sysdep/win/wmi.h
rename to source/lib/sysdep/os/win/wmi.h
diff --git a/source/lib/sysdep/win/wnuma.cpp b/source/lib/sysdep/os/win/wnuma.cpp
similarity index 100%
rename from source/lib/sysdep/win/wnuma.cpp
rename to source/lib/sysdep/os/win/wnuma.cpp
diff --git a/source/lib/sysdep/win/wposix/crt_posix.h b/source/lib/sysdep/os/win/wposix/crt_posix.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/crt_posix.h
rename to source/lib/sysdep/os/win/wposix/crt_posix.h
diff --git a/source/lib/sysdep/win/wposix/no_crt_posix.h b/source/lib/sysdep/os/win/wposix/no_crt_posix.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/no_crt_posix.h
rename to source/lib/sysdep/os/win/wposix/no_crt_posix.h
diff --git a/source/lib/sysdep/win/wposix/waio.cpp b/source/lib/sysdep/os/win/wposix/waio.cpp
similarity index 100%
rename from source/lib/sysdep/win/wposix/waio.cpp
rename to source/lib/sysdep/os/win/wposix/waio.cpp
diff --git a/source/lib/sysdep/win/wposix/waio.h b/source/lib/sysdep/os/win/wposix/waio.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/waio.h
rename to source/lib/sysdep/os/win/wposix/waio.h
diff --git a/source/lib/sysdep/win/wposix/wdlfcn.cpp b/source/lib/sysdep/os/win/wposix/wdlfcn.cpp
similarity index 100%
rename from source/lib/sysdep/win/wposix/wdlfcn.cpp
rename to source/lib/sysdep/os/win/wposix/wdlfcn.cpp
diff --git a/source/lib/sysdep/win/wposix/wdlfcn.h b/source/lib/sysdep/os/win/wposix/wdlfcn.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/wdlfcn.h
rename to source/lib/sysdep/os/win/wposix/wdlfcn.h
diff --git a/source/lib/sysdep/win/wposix/werrno.h b/source/lib/sysdep/os/win/wposix/werrno.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/werrno.h
rename to source/lib/sysdep/os/win/wposix/werrno.h
diff --git a/source/lib/sysdep/win/wposix/wfilesystem.cpp b/source/lib/sysdep/os/win/wposix/wfilesystem.cpp
similarity index 100%
rename from source/lib/sysdep/win/wposix/wfilesystem.cpp
rename to source/lib/sysdep/os/win/wposix/wfilesystem.cpp
diff --git a/source/lib/sysdep/win/wposix/wfilesystem.h b/source/lib/sysdep/os/win/wposix/wfilesystem.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/wfilesystem.h
rename to source/lib/sysdep/os/win/wposix/wfilesystem.h
diff --git a/source/lib/sysdep/win/wposix/wmman.cpp b/source/lib/sysdep/os/win/wposix/wmman.cpp
similarity index 100%
rename from source/lib/sysdep/win/wposix/wmman.cpp
rename to source/lib/sysdep/os/win/wposix/wmman.cpp
diff --git a/source/lib/sysdep/win/wposix/wmman.h b/source/lib/sysdep/os/win/wposix/wmman.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/wmman.h
rename to source/lib/sysdep/os/win/wposix/wmman.h
diff --git a/source/lib/sysdep/win/wposix/wposix.cpp b/source/lib/sysdep/os/win/wposix/wposix.cpp
similarity index 100%
rename from source/lib/sysdep/win/wposix/wposix.cpp
rename to source/lib/sysdep/os/win/wposix/wposix.cpp
diff --git a/source/lib/sysdep/win/wposix/wposix.h b/source/lib/sysdep/os/win/wposix/wposix.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/wposix.h
rename to source/lib/sysdep/os/win/wposix/wposix.h
diff --git a/source/lib/sysdep/win/wposix/wposix_internal.h b/source/lib/sysdep/os/win/wposix/wposix_internal.h
similarity index 72%
rename from source/lib/sysdep/win/wposix/wposix_internal.h
rename to source/lib/sysdep/os/win/wposix/wposix_internal.h
index b791531e7a..07028fe122 100644
--- a/source/lib/sysdep/win/wposix/wposix_internal.h
+++ b/source/lib/sysdep/os/win/wposix/wposix_internal.h
@@ -1,9 +1,9 @@
 #ifndef INCLUDED_WPOSIX_INTERNAL
 #define INCLUDED_WPOSIX_INTERNAL
 
-#include "lib/sysdep/win/win.h"
-#include "lib/sysdep/win/winit.h"
-#include "lib/sysdep/win/wutil.h"
+#include "lib/sysdep/os/win/win.h"
+#include "lib/sysdep/os/win/winit.h"
+#include "lib/sysdep/os/win/wutil.h"
 
 // cast intptr_t to HANDLE; centralized for easier changing, e.g. avoiding
 // warnings. i = -1 converts to INVALID_HANDLE_VALUE (same value).
diff --git a/source/lib/sysdep/win/wposix/wposix_types.h b/source/lib/sysdep/os/win/wposix/wposix_types.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/wposix_types.h
rename to source/lib/sysdep/os/win/wposix/wposix_types.h
diff --git a/source/lib/sysdep/win/wposix/wpthread.cpp b/source/lib/sysdep/os/win/wposix/wpthread.cpp
similarity index 100%
rename from source/lib/sysdep/win/wposix/wpthread.cpp
rename to source/lib/sysdep/os/win/wposix/wpthread.cpp
diff --git a/source/lib/sysdep/win/wposix/wpthread.h b/source/lib/sysdep/os/win/wposix/wpthread.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/wpthread.h
rename to source/lib/sysdep/os/win/wposix/wpthread.h
diff --git a/source/lib/sysdep/win/wposix/wsock.cpp b/source/lib/sysdep/os/win/wposix/wsock.cpp
similarity index 98%
rename from source/lib/sysdep/win/wposix/wsock.cpp
rename to source/lib/sysdep/os/win/wposix/wsock.cpp
index 9f958dce66..7622d0c026 100644
--- a/source/lib/sysdep/win/wposix/wsock.cpp
+++ b/source/lib/sysdep/os/win/wposix/wsock.cpp
@@ -11,7 +11,7 @@
 #include "precompiled.h"
 #include "wsock.h"
 
-#include "lib/sysdep/win/wdll_delay_load.h"
+#include "lib/sysdep/os/win/wdll_delay_load.h"
 #include "wposix_internal.h"
 #include "wsock_internal.h"
 #include "lib/module_init.h"
diff --git a/source/lib/sysdep/win/wposix/wsock.h b/source/lib/sysdep/os/win/wposix/wsock.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/wsock.h
rename to source/lib/sysdep/os/win/wposix/wsock.h
diff --git a/source/lib/sysdep/win/wposix/wsock_internal.h b/source/lib/sysdep/os/win/wposix/wsock_internal.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/wsock_internal.h
rename to source/lib/sysdep/os/win/wposix/wsock_internal.h
diff --git a/source/lib/sysdep/win/wposix/wterminal.cpp b/source/lib/sysdep/os/win/wposix/wterminal.cpp
similarity index 100%
rename from source/lib/sysdep/win/wposix/wterminal.cpp
rename to source/lib/sysdep/os/win/wposix/wterminal.cpp
diff --git a/source/lib/sysdep/win/wposix/wterminal.h b/source/lib/sysdep/os/win/wposix/wterminal.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/wterminal.h
rename to source/lib/sysdep/os/win/wposix/wterminal.h
diff --git a/source/lib/sysdep/win/wposix/wtime.cpp b/source/lib/sysdep/os/win/wposix/wtime.cpp
similarity index 98%
rename from source/lib/sysdep/win/wposix/wtime.cpp
rename to source/lib/sysdep/os/win/wposix/wtime.cpp
index d3264d3e8a..beaa949251 100644
--- a/source/lib/sysdep/win/wposix/wtime.cpp
+++ b/source/lib/sysdep/os/win/wposix/wtime.cpp
@@ -17,7 +17,7 @@
 
 #include "wposix_internal.h"
 #include "lib/sysdep/cpu.h"				// cpu_i64FromDouble
-#include "lib/sysdep/win/whrt/whrt.h"
+#include "lib/sysdep/os/win/whrt/whrt.h"
 
 WINIT_REGISTER_MAIN_INIT(wtime_Init);	// whrt -> wtime
 
diff --git a/source/lib/sysdep/win/wposix/wtime.h b/source/lib/sysdep/os/win/wposix/wtime.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/wtime.h
rename to source/lib/sysdep/os/win/wposix/wtime.h
diff --git a/source/lib/sysdep/win/wposix/wtime_internal.h b/source/lib/sysdep/os/win/wposix/wtime_internal.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/wtime_internal.h
rename to source/lib/sysdep/os/win/wposix/wtime_internal.h
diff --git a/source/lib/sysdep/win/wposix/wutsname.cpp b/source/lib/sysdep/os/win/wposix/wutsname.cpp
similarity index 100%
rename from source/lib/sysdep/win/wposix/wutsname.cpp
rename to source/lib/sysdep/os/win/wposix/wutsname.cpp
diff --git a/source/lib/sysdep/win/wposix/wutsname.h b/source/lib/sysdep/os/win/wposix/wutsname.h
similarity index 100%
rename from source/lib/sysdep/win/wposix/wutsname.h
rename to source/lib/sysdep/os/win/wposix/wutsname.h
diff --git a/source/lib/sysdep/win/wprintf.cpp b/source/lib/sysdep/os/win/wprintf.cpp
similarity index 100%
rename from source/lib/sysdep/win/wprintf.cpp
rename to source/lib/sysdep/os/win/wprintf.cpp
diff --git a/source/lib/sysdep/win/wprofiler.cpp b/source/lib/sysdep/os/win/wprofiler.cpp
similarity index 100%
rename from source/lib/sysdep/win/wprofiler.cpp
rename to source/lib/sysdep/os/win/wprofiler.cpp
diff --git a/source/lib/sysdep/win/wsdl.cpp b/source/lib/sysdep/os/win/wsdl.cpp
similarity index 99%
rename from source/lib/sysdep/win/wsdl.cpp
rename to source/lib/sysdep/os/win/wsdl.cpp
index b504109a3d..037b6c3460 100644
--- a/source/lib/sysdep/win/wsdl.cpp
+++ b/source/lib/sysdep/os/win/wsdl.cpp
@@ -26,7 +26,7 @@
 #include "lib/module_init.h"
 #include "wutil.h"
 #include "winit.h"
-#include "lib/sysdep/win/wmi.h"	// for SDL_GetVideoInfo
+#include "lib/sysdep/os/win/wmi.h"	// for SDL_GetVideoInfo
 
 #if MSC_VERSION
 #pragma comment(lib, "user32.lib")
diff --git a/source/lib/sysdep/win/wsdl.h b/source/lib/sysdep/os/win/wsdl.h
similarity index 100%
rename from source/lib/sysdep/win/wsdl.h
rename to source/lib/sysdep/os/win/wsdl.h
diff --git a/source/lib/sysdep/win/wseh.cpp b/source/lib/sysdep/os/win/wseh.cpp
similarity index 100%
rename from source/lib/sysdep/win/wseh.cpp
rename to source/lib/sysdep/os/win/wseh.cpp
diff --git a/source/lib/sysdep/win/wseh.h b/source/lib/sysdep/os/win/wseh.h
similarity index 100%
rename from source/lib/sysdep/win/wseh.h
rename to source/lib/sysdep/os/win/wseh.h
diff --git a/source/lib/sysdep/win/wsnd.cpp b/source/lib/sysdep/os/win/wsnd.cpp
similarity index 100%
rename from source/lib/sysdep/win/wsnd.cpp
rename to source/lib/sysdep/os/win/wsnd.cpp
diff --git a/source/lib/sysdep/win/wstartup.cpp b/source/lib/sysdep/os/win/wstartup.cpp
similarity index 100%
rename from source/lib/sysdep/win/wstartup.cpp
rename to source/lib/sysdep/os/win/wstartup.cpp
diff --git a/source/lib/sysdep/win/wstartup.h b/source/lib/sysdep/os/win/wstartup.h
similarity index 100%
rename from source/lib/sysdep/win/wstartup.h
rename to source/lib/sysdep/os/win/wstartup.h
diff --git a/source/lib/sysdep/win/wsysdep.cpp b/source/lib/sysdep/os/win/wsysdep.cpp
similarity index 100%
rename from source/lib/sysdep/win/wsysdep.cpp
rename to source/lib/sysdep/os/win/wsysdep.cpp
diff --git a/source/lib/sysdep/win/wutil.cpp b/source/lib/sysdep/os/win/wutil.cpp
similarity index 100%
rename from source/lib/sysdep/win/wutil.cpp
rename to source/lib/sysdep/os/win/wutil.cpp
diff --git a/source/lib/sysdep/win/wutil.h b/source/lib/sysdep/os/win/wutil.h
similarity index 100%
rename from source/lib/sysdep/win/wutil.h
rename to source/lib/sysdep/os/win/wutil.h
diff --git a/source/lib/timer.cpp b/source/lib/timer.cpp
index 72a711372e..b37c22186b 100644
--- a/source/lib/timer.cpp
+++ b/source/lib/timer.cpp
@@ -19,14 +19,14 @@
 #include "lib/posix/posix_time.h"
 #include "lib/sysdep/cpu.h"
 #if OS_WIN
-#include "lib/sysdep/win/whrt/whrt.h"
+#include "lib/sysdep/os/win/whrt/whrt.h"
 #endif
 #if OS_UNIX
 # include <unistd.h>
 #endif
 #include "lib/config2.h"	// CONFIG2_TIMER_ALLOW_RDTSC
 #if (ARCH_IA32 || ARCH_AMD64) && CONFIG2_TIMER_ALLOW_RDTSC
-# include "lib/sysdep/x86_x64/x86_x64.h"	// x86_x64_rdtsc
+# include "lib/sysdep/arch/x86_x64/x86_x64.h"	// x86_x64_rdtsc
 #endif
 
 #if OS_UNIX || OS_WIN
diff --git a/source/network/SocketBase.cpp b/source/network/SocketBase.cpp
index 3c28456f49..0428224b19 100644
--- a/source/network/SocketBase.cpp
+++ b/source/network/SocketBase.cpp
@@ -1,8 +1,8 @@
 #include "precompiled.h"
 
 #if OS_WIN
-#include "lib/sysdep/win/win.h"
-#include "lib/sysdep/win/wposix/wsock_internal.h"
+#include "lib/sysdep/os/win/win.h"
+#include "lib/sysdep/os/win/wposix/wsock_internal.h"
 #endif
 
 #include "Network.h"
diff --git a/source/ps/Profile.cpp b/source/ps/Profile.cpp
index 9391713a9c..929d5a69e6 100644
--- a/source/ps/Profile.cpp
+++ b/source/ps/Profile.cpp
@@ -13,7 +13,7 @@
 #include "lib/timer.h"
 
 #if OS_WIN
-#include "lib/sysdep/win/wdbg_heap.h"
+#include "lib/sysdep/os/win/wdbg_heap.h"
 #endif
 #if defined(__GLIBC__) && !defined(NDEBUG)
 # define GLIBC_MALLOC_HOOK
diff --git a/source/ps/Util.cpp b/source/ps/Util.cpp
index 2dcf628444..261ee9f423 100644
--- a/source/ps/Util.cpp
+++ b/source/ps/Util.cpp
@@ -9,7 +9,7 @@
 #include "lib/sysdep/gfx.h"
 #include "lib/sysdep/snd.h"
 #include "lib/sysdep/os_cpu.h"
-#include "lib/sysdep/x86_x64/topology.h"
+#include "lib/sysdep/arch/x86_x64/topology.h"
 #include "lib/tex/tex.h"
 #include "lib/file/io/io_align.h"	// BLOCK_SIZE
 
diff --git a/source/test_setup.cpp b/source/test_setup.cpp
index acade9bf2a..41f9cce414 100644
--- a/source/test_setup.cpp
+++ b/source/test_setup.cpp
@@ -10,7 +10,7 @@
 #include <cxxtest/GlobalFixture.h>
 
 #if OS_WIN
-#include "lib/sysdep/win/wdbg_heap.h"
+#include "lib/sysdep/os/win/wdbg_heap.h"
 #endif
 
 class LeakReporter : public CxxTest::GlobalFixture