diff --git a/src/xrCore/CMakeLists.txt b/src/xrCore/CMakeLists.txt
index 0792f7a65f7..f9b7f45c5e2 100644
--- a/src/xrCore/CMakeLists.txt
+++ b/src/xrCore/CMakeLists.txt
@@ -3,11 +3,12 @@ set(SOURCES
   cpuid.cpp
   crc32.cpp
   dump_string.cpp
-  file_stream_reader.cpp
-  FileSystem.cpp
-  FileSystem_borland.cpp
+#  file_stream_reader.cpp
+#  FileSystem.cpp
+#  FileSystem_borland.cpp
+##  FileSystem_posix.cpp
   FMesh.cpp
-  FS.cpp
+#  FS.cpp
   FTimer.cpp
   LocatorAPI.cpp
   LocatorAPI_auth.cpp
@@ -36,43 +37,6 @@ set(SOURCES
   _math.cpp
   _sphere.cpp
   _std_extensions.cpp
-#  clsid.cpp
-#  cpuid.cpp
-#  crc32.cpp
-#  doug_lea_allocator.cpp
-#  dump_string.cpp
-#  FMesh.cpp
-#  FS.cpp
-#  FTimer.cpp
-#  LocatorAPI.cpp
-#  LocatorAPI_auth.cpp
-#  LocatorAPI_defs.cpp
-#  log.cpp
-#  LzHuf.cpp
-#  memory_allocation_stats.cpp
-#  memory_monitor.cpp
-#  memory_usage.cpp
-#  Model.cpp
-#  NET_utils.cpp
-#  os_clipboard.cpp
-#  ppmd_compressor.cpp
-#  stdafx.cpp
-#  string_concatenations.cpp
-#  xrCore.cpp
-#  ModuleLookup.cpp
-#  xrDebug.cpp
-#  xrMemory.cpp
-#  xrMemory_debug.cpp
-#  xrMemory_POOL.cpp
-#  xrsharedmem.cpp
-#  xrstring.cpp
-#  Xr_ini.cpp
-#  xr_shared.cpp
-#  xr_trims.cpp
-#  _compressed_normal.cpp
-#  _math.cpp
-#  _sphere.cpp
-#  _std_extensions.cpp
 )
 
 set(HEADERS
@@ -110,7 +74,7 @@ set(HEADERS
   PPMdType.h
   resource.h
   stdafx.h
-  Stream_Reader.h
+  stream_reader.h
   stream_reader_inline.h
   string_concatenations.h
   string_concatenations_inline.h
diff --git a/src/xrCore/FS.cpp b/src/xrCore/FS.cpp
index 3fc1efa53a7..6f03c822c8e 100644
--- a/src/xrCore/FS.cpp
+++ b/src/xrCore/FS.cpp
@@ -1,14 +1,27 @@
 #include "stdafx.h"
 #pragma hdrstop
 
-#include "fs_internal.h"
+#include "FS_internal.h"
 
 #pragma warning(push)
 #pragma warning(disable : 4995)
+#ifdef WINDOWS
 #include <io.h>
 #include <direct.h>
 #include <fcntl.h>
 #include <sys\stat.h>
+#else
+/*
+#include <sys/stat.h>
+
+long _filelength(char *f)
+{
+    struct stat st;
+    stat(f, &st);
+    return st.st_size;
+}
+*/
+#endif
 #pragma warning(pop)
 
 #ifdef M_BORLAND
diff --git a/src/xrCore/FS_internal.h b/src/xrCore/FS_internal.h
index 9b8ec515885..03317179ecd 100644
--- a/src/xrCore/FS_internal.h
+++ b/src/xrCore/FS_internal.h
@@ -3,10 +3,12 @@
 #pragma once
 
 #include "lzhuf.h"
+#ifdef WINDOWS
 #include <io.h>
 #include <fcntl.h>
 #include <sys\stat.h>
 #include <share.h>
+#endif
 
 void* FileDownload(LPCSTR fn, u32* pdwSize = NULL);
 void FileCompress(const char* fn, const char* sign, void* data, u32 size);
@@ -46,12 +48,14 @@ class CFileWriter : public IWriter
         {
             fclose(hf);
             // release RO attrib
+#ifdef WINDOWS
             DWORD dwAttr = GetFileAttributes(fName.c_str());
             if ((dwAttr != u32(-1)) && (dwAttr & FILE_ATTRIBUTE_READONLY))
             {
                 dwAttr &= ~FILE_ATTRIBUTE_READONLY;
                 SetFileAttributes(fName.c_str(), dwAttr);
             }
+#endif // Probably not needed.
         }
     }
     // kernel
diff --git a/src/xrCore/FileSystem.cpp b/src/xrCore/FileSystem.cpp
index 3c11d8ef0c2..838992bc16c 100644
--- a/src/xrCore/FileSystem.cpp
+++ b/src/xrCore/FileSystem.cpp
@@ -5,9 +5,11 @@
 #include "stdafx.h"
 #pragma hdrstop
 
+#ifdef WINDOWS
 #include "cderr.h"
 #include "commdlg.h"
 #include "vfw.h"
+#endif
 
 std::unique_ptr<EFS_Utils> xr_EFS;
 //----------------------------------------------------
diff --git a/src/xrCore/FileSystem_borland.cpp b/src/xrCore/FileSystem_borland.cpp
index 6e2b3fb511e..0b6f177f4b1 100644
--- a/src/xrCore/FileSystem_borland.cpp
+++ b/src/xrCore/FileSystem_borland.cpp
@@ -7,11 +7,13 @@
 
 #include "FileSystem.h"
 
+#ifdef WINDOWS
 #include <io.h>
 #include <fcntl.h>
 #include <sys\stat.h>
 
 #include <Shlobj.h>
+#endif
 
 //#pragma comment(lib, "OSDialogB.lib")
 
diff --git a/src/xrCore/LocatorAPI.cpp b/src/xrCore/LocatorAPI.cpp
index 75e455fbcf7..3336839a835 100644
--- a/src/xrCore/LocatorAPI.cpp
+++ b/src/xrCore/LocatorAPI.cpp
@@ -7,9 +7,11 @@
 
 #pragma warning(push)
 #pragma warning(disable : 4995)
+#ifdef WINDOWS
 #include <direct.h>
 #include <fcntl.h>
 #include <sys/stat.h>
+#endif
 #pragma warning(pop)
 
 #include "FS_internal.h"
diff --git a/src/xrCore/Stream_Reader.h b/src/xrCore/stream_reader.h
similarity index 100%
rename from src/xrCore/Stream_Reader.h
rename to src/xrCore/stream_reader.h
diff --git a/src/xrCore/stream_reader_inline.h b/src/xrCore/stream_reader_inline.h
index 9af5f02a7b3..e45db267259 100644
--- a/src/xrCore/stream_reader_inline.h
+++ b/src/xrCore/stream_reader_inline.h
@@ -16,7 +16,14 @@ IC CStreamReader& CStreamReader::operator=(const CStreamReader&)
 }
 
 IC const HANDLE& CStreamReader::file_mapping_handle() const { return (m_file_mapping_handle); }
-IC void CStreamReader::unmap() { UnmapViewOfFile(m_current_map_view_of_file); }
+IC void CStreamReader::unmap()
+{
+#ifdef WINDOWS
+    UnmapViewOfFile(m_current_map_view_of_file);
+#else
+#warning TODO: Port CStreamReader::unmap()
+#endif
+}
 IC void CStreamReader::remap(const u32& new_offset)
 {
     unmap();