diff --git a/uppsrc/plugin/zstd_legacy/Compress.cpp b/uppsrc/plugin/zstd_legacy/Compress.cpp
index 07d93ad9f..10b39f246 100644
--- a/uppsrc/plugin/zstd_legacy/Compress.cpp
+++ b/uppsrc/plugin/zstd_legacy/Compress.cpp
@@ -2,6 +2,8 @@
 
 namespace Upp {
 	
+namespace Legacy {
+	
 // we simply store data as series of complete Zstd frames, as library gives us no easy way
 // to do it in MT
 
@@ -133,3 +135,5 @@ ZstdCompressStream::~ZstdCompressStream()
 }
 
 };
+
+};
diff --git a/uppsrc/plugin/zstd_legacy/Decompress.cpp b/uppsrc/plugin/zstd_legacy/Decompress.cpp
index 7742ccefc..c7bd26231 100644
--- a/uppsrc/plugin/zstd_legacy/Decompress.cpp
+++ b/uppsrc/plugin/zstd_legacy/Decompress.cpp
@@ -4,6 +4,7 @@
 
 namespace Upp {
 
+namespace Legacy {
 
 void ZstdDecompressStream::Init()
 {
@@ -271,3 +272,5 @@ bool IsZstd(Stream& s)
 }
 
 };
+
+};
diff --git a/uppsrc/plugin/zstd_legacy/Lib.cpp b/uppsrc/plugin/zstd_legacy/Lib.cpp
new file mode 100644
index 000000000..a26bc1563
--- /dev/null
+++ b/uppsrc/plugin/zstd_legacy/Lib.cpp
@@ -0,0 +1,18 @@
+namespace Upp {
+	
+namespace Legacy {
+
+#include "lib/entropy_common.c"
+#include "lib/fse_compress.c"
+#include "lib/fse_decompress.c"
+#include "lib/huf_compress.c"
+#include "lib/huf_decompress.c"
+#include "lib/zbuff_compress.c"
+#include "lib/zbuff_decompress.c"
+#include "lib/zstd_common.c"
+#include "lib/zstd_compress.c"
+#include "lib/zstd_decompress.c"
+
+};
+
+};
diff --git a/uppsrc/plugin/zstd_legacy/Util.cpp b/uppsrc/plugin/zstd_legacy/Util.cpp
index 95a7a92b9..e01856e46 100644
--- a/uppsrc/plugin/zstd_legacy/Util.cpp
+++ b/uppsrc/plugin/zstd_legacy/Util.cpp
@@ -1,9 +1,11 @@
 #include "zstd.h"
 
 namespace Upp {
-	
-void sCompressStreamCopy_(Stream& out, Stream& in, Gate<int64, int64> progress, Stream& orig_in, int64 insz);
 
+void sCompressStreamCopy_(Stream& out, Stream& in, Gate<int64, int64> progress, Stream& orig_in, int64 insz);
+	
+namespace Legacy {
+	
 static int64 sZstdCompress(Stream& out, Stream& in, int64 size, Gate<int64, int64> progress, bool co)
 {
 	ZstdCompressStream outs(out);
@@ -104,4 +106,6 @@ String CoZstdDecompress(const String& s, Gate<int64, int64> progress)
 
 #endif
 
+};
+
 };
\ No newline at end of file
diff --git a/uppsrc/plugin/zstd_legacy/lib/bitstream.h b/uppsrc/plugin/zstd_legacy/lib/bitstream.h
index e96798fe4..89812b4b6 100644
--- a/uppsrc/plugin/zstd_legacy/lib/bitstream.h
+++ b/uppsrc/plugin/zstd_legacy/lib/bitstream.h
@@ -35,11 +35,6 @@
 #ifndef BITSTREAM_H_MODULE
 #define BITSTREAM_H_MODULE
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
-
 /*
 *  This API consists of small unitary functions, which must be inlined for best performance.
 *  Since link-time-optimization is not available for all compilers,
@@ -407,8 +402,4 @@ MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* DStream)
     return ((DStream->ptr == DStream->start) && (DStream->bitsConsumed == sizeof(DStream->bitContainer)*8));
 }
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* BITSTREAM_H_MODULE */
diff --git a/uppsrc/plugin/zstd_legacy/lib/error_private.h b/uppsrc/plugin/zstd_legacy/lib/error_private.h
index 889061496..e1c73c368 100644
--- a/uppsrc/plugin/zstd_legacy/lib/error_private.h
+++ b/uppsrc/plugin/zstd_legacy/lib/error_private.h
@@ -35,11 +35,6 @@
 #ifndef ERROR_H_MODULE
 #define ERROR_H_MODULE
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
-
 /* ****************************************
 *  Dependencies
 ******************************************/
@@ -118,8 +113,4 @@ ERR_STATIC const char* ERR_getErrorName(size_t code)
     return ERR_getErrorString(ERR_getErrorCode(code));
 }
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* ERROR_H_MODULE */
diff --git a/uppsrc/plugin/zstd_legacy/lib/error_public.h b/uppsrc/plugin/zstd_legacy/lib/error_public.h
index 29050b3b3..5ec8aaf5e 100644
--- a/uppsrc/plugin/zstd_legacy/lib/error_public.h
+++ b/uppsrc/plugin/zstd_legacy/lib/error_public.h
@@ -33,11 +33,6 @@
 #ifndef ERROR_PUBLIC_H_MODULE
 #define ERROR_PUBLIC_H_MODULE
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
-
 /* ****************************************
 *  error codes list
 ******************************************/
@@ -69,9 +64,4 @@ typedef enum {
 ZSTD_ErrorCode ZSTD_getErrorCode(size_t functionResult);
 const char* ZSTD_getErrorString(ZSTD_ErrorCode code);
 
-
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* ERROR_PUBLIC_H_MODULE */
diff --git a/uppsrc/plugin/zstd_legacy/lib/fse.h b/uppsrc/plugin/zstd_legacy/lib/fse.h
index e711d0135..ef81a8979 100644
--- a/uppsrc/plugin/zstd_legacy/lib/fse.h
+++ b/uppsrc/plugin/zstd_legacy/lib/fse.h
@@ -34,11 +34,6 @@
 #ifndef FSE_H
 #define FSE_H
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
-
 /*-*****************************************
 *  Dependencies
 ******************************************/
@@ -620,9 +615,4 @@ MEM_STATIC unsigned FSE_endOfDState(const FSE_DState_t* DStatePtr)
 
 #endif /* FSE_STATIC_LINKING_ONLY */
 
-
-#if defined (__cplusplus)
-}
-#endif
-
 #endif  /* FSE_H */
diff --git a/uppsrc/plugin/zstd_legacy/lib/fse_compress.c b/uppsrc/plugin/zstd_legacy/lib/fse_compress.c
index 192d55026..53592d767 100644
--- a/uppsrc/plugin/zstd_legacy/lib/fse_compress.c
+++ b/uppsrc/plugin/zstd_legacy/lib/fse_compress.c
@@ -190,8 +190,6 @@ size_t FSE_NCountWriteBound(unsigned maxSymbolValue, unsigned tableLog)
     return maxSymbolValue ? maxHeaderSize : FSE_NCOUNTBOUND;  /* maxSymbolValue==0 ? use default */
 }
 
-static short FSE_abs(short a) { return a<0 ? -a : a; }
-
 static size_t FSE_writeNCount_generic (void* header, size_t headerBufferSize,
                                        const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog,
                                        unsigned writeIsSafe)
diff --git a/uppsrc/plugin/zstd_legacy/lib/huf.h b/uppsrc/plugin/zstd_legacy/lib/huf.h
index 3b837f101..911e952af 100644
--- a/uppsrc/plugin/zstd_legacy/lib/huf.h
+++ b/uppsrc/plugin/zstd_legacy/lib/huf.h
@@ -34,11 +34,6 @@
 #ifndef HUF_H_298734234
 #define HUF_H_298734234
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
-
 /* *** Dependencies *** */
 #include <stddef.h>    /* size_t */
 
@@ -220,9 +215,4 @@ size_t HUF_decompress1X4_usingDTable(void* dst, size_t maxDstSize, const void* c
 
 #endif /* HUF_STATIC_LINKING_ONLY */
 
-
-#if defined (__cplusplus)
-}
-#endif
-
 #endif   /* HUF_H_298734234 */
diff --git a/uppsrc/plugin/zstd_legacy/lib/mem.h b/uppsrc/plugin/zstd_legacy/lib/mem.h
index 9156bfda9..1d3ca4371 100644
--- a/uppsrc/plugin/zstd_legacy/lib/mem.h
+++ b/uppsrc/plugin/zstd_legacy/lib/mem.h
@@ -35,10 +35,6 @@
 #ifndef MEM_H_MODULE
 #define MEM_H_MODULE
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 /*-****************************************
 *  Dependencies
 ******************************************/
@@ -369,9 +365,5 @@ MEM_STATIC U32 MEM_readMINMATCH(const void* memPtr, U32 length)
     }
 }
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif /* MEM_H_MODULE */
 
diff --git a/uppsrc/plugin/zstd_legacy/lib/zbuff.h b/uppsrc/plugin/zstd_legacy/lib/zbuff.h
index 7820db26d..09571fc85 100644
--- a/uppsrc/plugin/zstd_legacy/lib/zbuff.h
+++ b/uppsrc/plugin/zstd_legacy/lib/zbuff.h
@@ -31,10 +31,6 @@
 #ifndef ZSTD_BUFFERED_H_23987
 #define ZSTD_BUFFERED_H_23987
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 /* *************************************
 *  Dependencies
 ***************************************/
@@ -189,9 +185,4 @@ ZSTDLIB_API size_t ZBUFF_compressInit_advanced(ZBUFF_CCtx* zbc,
 
 #endif /* ZBUFF_STATIC_LINKING_ONLY */
 
-
-#if defined (__cplusplus)
-}
-#endif
-
 #endif  /* ZSTD_BUFFERED_H_23987 */
diff --git a/uppsrc/plugin/zstd_legacy/lib/zbuff_decompress.c b/uppsrc/plugin/zstd_legacy/lib/zbuff_decompress.c
index e74fb5d1f..ca1185944 100644
--- a/uppsrc/plugin/zstd_legacy/lib/zbuff_decompress.c
+++ b/uppsrc/plugin/zstd_legacy/lib/zbuff_decompress.c
@@ -137,15 +137,6 @@ size_t ZBUFF_decompressInit(ZBUFF_DCtx* zbd)
 }
 
 
-/* internal util function */
-MEM_STATIC size_t ZBUFF_limitCopy(void* dst, size_t dstCapacity, const void* src, size_t srcSize)
-{
-    size_t const length = MIN(dstCapacity, srcSize);
-    memcpy(dst, src, length);
-    return length;
-}
-
-
 /* *** Decompression *** */
 
 size_t ZBUFF_decompressContinue(ZBUFF_DCtx* zbd,
diff --git a/uppsrc/plugin/zstd_legacy/lib/zstd.h b/uppsrc/plugin/zstd_legacy/lib/zstd.h
index 47bae1157..eefdb95a8 100644
--- a/uppsrc/plugin/zstd_legacy/lib/zstd.h
+++ b/uppsrc/plugin/zstd_legacy/lib/zstd.h
@@ -32,10 +32,6 @@
 #ifndef ZSTD_H_235446
 #define ZSTD_H_235446
 
-#if defined (__cplusplus)
-extern "C" {
-#endif
-
 /*-*************************************
 *  Dependencies
 ***************************************/
@@ -468,8 +464,4 @@ ZSTDLIB_API size_t ZSTD_insertBlock(ZSTD_DCtx* dctx, const void* blockStart, siz
 
 #endif   /* ZSTD_STATIC_LINKING_ONLY */
 
-#if defined (__cplusplus)
-}
-#endif
-
 #endif  /* ZSTD_H_235446 */
diff --git a/uppsrc/plugin/zstd_legacy/zstd.h b/uppsrc/plugin/zstd_legacy/zstd.h
index 03d95d938..9c80e4f6a 100644
--- a/uppsrc/plugin/zstd_legacy/zstd.h
+++ b/uppsrc/plugin/zstd_legacy/zstd.h
@@ -1,13 +1,15 @@
-#ifndef _plugin_zstd_zstd_h_
-#define _plugin_zstd_zstd_h_
+#ifndef _plugin_zstd_zstd_legacy_h_
+#define _plugin_zstd_zstd_legacy_h_
 
 #include <Core/Core.h>
 
+namespace Upp {
+	
+namespace Legacy {
+
 #define ZSTD_STATIC_LINKING_ONLY
 #include "lib/zstd.h"
 
-namespace Upp {
-
 class ZstdCompressStream : public Stream  {
 public:
 	virtual   void  Close();
@@ -103,17 +105,17 @@ String ZstdCompress(const String& s, Gate<int64, int64> progress = Null);
 String ZstdDecompress(const void *data, int64 len, Gate<int64, int64> progress = Null);
 String ZstdDecompress(const String& s, Gate<int64, int64> progress = Null);
 
-#ifdef _MULTITHREADED
 int64 CoZstdCompress(Stream& out, Stream& in, Gate<int64, int64> progress = Null);
 int64 CoZstdDecompress(Stream& out, Stream& in, Gate<int64, int64> progress = Null);
 String CoZstdCompress(const void *data, int64 len, Gate<int64, int64> progress = Null);
 String CoZstdCompress(const String& s, Gate<int64, int64> progress = Null);
 String CoZstdDecompress(const void *data, int64 len, Gate<int64, int64> progress = Null);
 String CoZstdDecompress(const String& s, Gate<int64, int64> progress = Null);
-#endif
 
 bool IsZstd(Stream& s);
 
 }
 
+}
+
 #endif
diff --git a/uppsrc/plugin/zstd_legacy/zstd_legacy.upp b/uppsrc/plugin/zstd_legacy/zstd_legacy.upp
index 395d6cea5..52a0db9ab 100644
--- a/uppsrc/plugin/zstd_legacy/zstd_legacy.upp
+++ b/uppsrc/plugin/zstd_legacy/zstd_legacy.upp
@@ -5,18 +5,8 @@ file
 	Compress.cpp,
 	Decompress.cpp,
 	Util.cpp,
+	Lib.cpp,
 	lib\zstd.h,
 	src.tpp,
-	Copying,
-	lib readonly separator,
-	lib\entropy_common.c,
-	lib\fse_compress.c,
-	lib\fse_decompress.c,
-	lib\huf_compress.c,
-	lib\huf_decompress.c,
-	lib\zbuff_compress.c,
-	lib\zbuff_decompress.c,
-	lib\zstd_common.c,
-	lib\zstd_compress.c,
-	lib\zstd_decompress.c;
+	Copying;