diff --git a/CHANGELOG b/CHANGELOG
index 44600267..3b882d4c 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -11,6 +11,7 @@ cli: Named pipes support, by @bimbashrestha
 cli: short tar's extension support, by @stokito
 cli: command --output-dir-flat= , generates target files into requested directory, by @senhuang42
 cli: commands --stream-size=# and --size-hint=#, by @nmagerko
+cli: command --exclude-compressed, by @shashank0791
 cli: faster `-t` test mode
 cli: improved some error messages, by @vangyzen
 cli: rare deadlock condition within dictionary builder, by @terrelln
diff --git a/README.md b/README.md
index 9c5f9201..c94c7882 100644
--- a/README.md
+++ b/README.md
@@ -43,7 +43,7 @@ on the [Silesia compression corpus].
 
 | Compressor name         | Ratio | Compression| Decompress.|
 | ---------------         | ------| -----------| ---------- |
-| **zstd 1.4.0 -1**       | 2.884 |   530 MB/s |  1360 MB/s |
+| **zstd 1.4.4 -1**       | 2.884 |   520 MB/s |  1600 MB/s |
 | zlib 1.2.11 -1          | 2.743 |   110 MB/s |   440 MB/s |
 | brotli 1.0.7 -0         | 2.701 |   430 MB/s |   470 MB/s |
 | quicklz 1.5.0 -1        | 2.238 |   600 MB/s |   800 MB/s |
diff --git a/appveyor.yml b/appveyor.yml
index 87fa5c12..dd2c02ac 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -173,8 +173,6 @@
       sh -e playTests.sh --test-large-data &&
       fullbench.exe -i1 &&
       fullbench.exe -i1 -P0 &&
-      fuzzer_VS2008_%PLATFORM%_Release.exe %FUZZERTEST% &&
-      fuzzer_VS2010_%PLATFORM%_Release.exe %FUZZERTEST% &&
       fuzzer_VS2012_%PLATFORM%_Release.exe %FUZZERTEST% &&
       fuzzer_VS2013_%PLATFORM%_Release.exe %FUZZERTEST% &&
       fuzzer_VS2015_%PLATFORM%_Release.exe %FUZZERTEST%
diff --git a/build/cmake/CMakeLists.txt b/build/cmake/CMakeLists.txt
index 33c05aee..9d0e7fb0 100644
--- a/build/cmake/CMakeLists.txt
+++ b/build/cmake/CMakeLists.txt
@@ -124,9 +124,13 @@ endif ()
 #-----------------------------------------------------------------------------
 add_subdirectory(lib)
 
+option(ZSTD_PROGRAMS_LINK_SHARED "PROGRAMS LINK SHARED" OFF)
+
 if (ZSTD_BUILD_PROGRAMS)
-    if (NOT ZSTD_BUILD_STATIC)
+    if (NOT ZSTD_BUILD_STATIC AND NOT ZSTD_PROGRAMS_LINK_SHARED)
         message(SEND_ERROR "You need to build static library to build zstd CLI")
+    elseif(NOT ZSTD_BUILD_SHARED AND ZSTD_PROGRAMS_LINK_SHARED)
+        message(SEND_ERROR "You need to build shared library to build zstd CLI")
     endif ()
 
     add_subdirectory(programs)
diff --git a/build/cmake/programs/CMakeLists.txt b/build/cmake/programs/CMakeLists.txt
index 8afd8350..b26e97d0 100644
--- a/build/cmake/programs/CMakeLists.txt
+++ b/build/cmake/programs/CMakeLists.txt
@@ -21,13 +21,19 @@ if (ZSTD_LEGACY_SUPPORT)
     include_directories(${PROGRAMS_LEGACY_DIR} ${LIBRARY_DIR}/legacy)
 endif ()
 
+if (ZSTD_PROGRAMS_LINK_SHARED)
+    set(PROGRAMS_ZSTD_LINK_TARGET libzstd_shared)
+else ()
+    set(PROGRAMS_ZSTD_LINK_TARGET libzstd_static)
+endif ()
+
 if (MSVC)
     set(MSVC_RESOURCE_DIR ${ZSTD_SOURCE_DIR}/build/VS2010/zstd)
     set(PlatformDependResources ${MSVC_RESOURCE_DIR}/zstd.rc)
 endif ()
 
 add_executable(zstd ${PROGRAMS_DIR}/zstdcli.c ${PROGRAMS_DIR}/util.c ${PROGRAMS_DIR}/timefn.c ${PROGRAMS_DIR}/fileio.c ${PROGRAMS_DIR}/benchfn.c ${PROGRAMS_DIR}/benchzstd.c ${PROGRAMS_DIR}/datagen.c ${PROGRAMS_DIR}/dibio.c ${PlatformDependResources})
-target_link_libraries(zstd libzstd_static)
+target_link_libraries(zstd ${PROGRAMS_ZSTD_LINK_TARGET})
 if (CMAKE_SYSTEM_NAME MATCHES "(Solaris|SunOS)")
     target_link_libraries(zstd rt)
 endif ()
@@ -68,7 +74,7 @@ if (UNIX)
         DESTINATION "${MAN_INSTALL_DIR}")
 
     add_executable(zstd-frugal ${PROGRAMS_DIR}/zstdcli.c ${PROGRAMS_DIR}/util.c ${PROGRAMS_DIR}/timefn.c ${PROGRAMS_DIR}/fileio.c)
-    target_link_libraries(zstd-frugal libzstd_static)
+    target_link_libraries(zstd-frugal ${PROGRAMS_ZSTD_LINK_TARGET})
     set_property(TARGET zstd-frugal APPEND PROPERTY COMPILE_DEFINITIONS "ZSTD_NOBENCH;ZSTD_NODICT")
 endif ()
 
diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index 07df9f04..35346b92 100644
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -2771,7 +2771,7 @@ static size_t ZSTD_checkDictNCount(short* normalizedCounter, unsigned dictMaxSym
 /*! ZSTD_loadZstdDictionary() :
  * @return : dictID, or an error code
  *  assumptions : magic number supposed already checked
- *                dictSize supposed > 8
+ *                dictSize supposed >= 8
  */
 static size_t ZSTD_loadZstdDictionary(ZSTD_compressedBlockState_t* bs,
                                       ZSTD_matchState_t* ms,
@@ -2788,7 +2788,7 @@ static size_t ZSTD_loadZstdDictionary(ZSTD_compressedBlockState_t* bs,
     size_t dictID;
 
     ZSTD_STATIC_ASSERT(HUF_WORKSPACE_SIZE >= (1<<MAX(MLFSELog,LLFSELog)));
-    assert(dictSize > 8);
+    assert(dictSize >= 8);
     assert(MEM_readLE32(dictPtr) == ZSTD_MAGIC_DICTIONARY);
 
     dictPtr += 4;   /* skip magic number */
@@ -2890,7 +2890,10 @@ ZSTD_compress_insertDictionary(ZSTD_compressedBlockState_t* bs,
                                void* workspace)
 {
     DEBUGLOG(4, "ZSTD_compress_insertDictionary (dictSize=%u)", (U32)dictSize);
-    if ((dict==NULL) || (dictSize<=8)) return 0;
+    if ((dict==NULL) || (dictSize<8)) {
+        RETURN_ERROR_IF(dictContentType == ZSTD_dct_fullDict, dictionary_wrong);
+        return 0;
+    }
 
     ZSTD_reset_compressedBlockState(bs);
 
@@ -2934,6 +2937,7 @@ static size_t ZSTD_compressBegin_internal(ZSTD_CCtx* cctx,
       && (cdict->dictContentSize > 0)
       && ( pledgedSrcSize < ZSTD_USE_CDICT_PARAMS_SRCSIZE_CUTOFF
         || pledgedSrcSize < cdict->dictContentSize * ZSTD_USE_CDICT_PARAMS_DICTSIZE_MULTIPLIER
+        || pledgedSrcSize == ZSTD_CONTENTSIZE_UNKNOWN
         || cdict->compressionLevel == 0)
       && (params->attachDictPref != ZSTD_dictForceLoad) ) {
         return ZSTD_resetCCtx_usingCDict(cctx, cdict, params, pledgedSrcSize, zbuff);
@@ -2941,7 +2945,7 @@ static size_t ZSTD_compressBegin_internal(ZSTD_CCtx* cctx,
 
     FORWARD_IF_ERROR( ZSTD_resetCCtx_internal(cctx, *params, pledgedSrcSize,
                                      ZSTDcrp_makeClean, zbuff) );
-    {   size_t const dictID = cdict ? 
+    {   size_t const dictID = cdict ?
                 ZSTD_compress_insertDictionary(
                         cctx->blockState.prevCBlock, &cctx->blockState.matchState,
                         &cctx->workspace, params, cdict->dictContent, cdict->dictContentSize,
@@ -3218,7 +3222,7 @@ static size_t ZSTD_initCDict_internal(
         ZSTDirp_reset,
         ZSTD_resetTarget_CDict));
     /* (Maybe) load the dictionary
-     * Skips loading the dictionary if it is <= 8 bytes.
+     * Skips loading the dictionary if it is < 8 bytes.
      */
     {   ZSTD_CCtx_params params;
         memset(&params, 0, sizeof(params));
@@ -3381,6 +3385,7 @@ size_t ZSTD_compressBegin_usingCDict_advanced(
     {   ZSTD_CCtx_params params = cctx->requestedParams;
         params.cParams = ( pledgedSrcSize < ZSTD_USE_CDICT_PARAMS_SRCSIZE_CUTOFF
                         || pledgedSrcSize < cdict->dictContentSize * ZSTD_USE_CDICT_PARAMS_DICTSIZE_MULTIPLIER
+                        || pledgedSrcSize == ZSTD_CONTENTSIZE_UNKNOWN
                         || cdict->compressionLevel == 0 )
                       && (params.attachDictPref != ZSTD_dictForceLoad) ?
                 ZSTD_getCParamsFromCDict(cdict)
diff --git a/lib/decompress/zstd_decompress.c b/lib/decompress/zstd_decompress.c
index ca47a667..dd4591b7 100644
--- a/lib/decompress/zstd_decompress.c
+++ b/lib/decompress/zstd_decompress.c
@@ -1096,7 +1096,7 @@ ZSTD_loadDEntropy(ZSTD_entropyDTables_t* entropy,
         size_t const dictContentSize = (size_t)(dictEnd - (dictPtr+12));
         for (i=0; i<3; i++) {
             U32 const rep = MEM_readLE32(dictPtr); dictPtr += 4;
-            RETURN_ERROR_IF(rep==0 || rep >= dictContentSize,
+            RETURN_ERROR_IF(rep==0 || rep > dictContentSize,
                             dictionary_corrupted);
             entropy->rep[i] = rep;
     }   }
@@ -1265,7 +1265,7 @@ size_t ZSTD_DCtx_loadDictionary_advanced(ZSTD_DCtx* dctx,
 {
     RETURN_ERROR_IF(dctx->streamStage != zdss_init, stage_wrong);
     ZSTD_clearDict(dctx);
-    if (dict && dictSize >= 8) {
+    if (dict && dictSize != 0) {
         dctx->ddictLocal = ZSTD_createDDict_advanced(dict, dictSize, dictLoadMethod, dictContentType, dctx->customMem);
         RETURN_ERROR_IF(dctx->ddictLocal == NULL, memory_allocation);
         dctx->ddict = dctx->ddictLocal;
diff --git a/lib/decompress/zstd_decompress_block.c b/lib/decompress/zstd_decompress_block.c
index cbb66c8d..767e5f9a 100644
--- a/lib/decompress/zstd_decompress_block.c
+++ b/lib/decompress/zstd_decompress_block.c
@@ -617,7 +617,7 @@ static void ZSTD_safecopy(BYTE* op, BYTE* const oend_w, BYTE const* ip, ptrdiff_
     ptrdiff_t const diff = op - ip;
     BYTE* const oend = op + length;
 
-    assert((ovtype == ZSTD_no_overlap && (diff <= -8 || diff >= 8)) ||
+    assert((ovtype == ZSTD_no_overlap && (diff <= -8 || diff >= 8 || op >= oend_w)) ||
            (ovtype == ZSTD_overlap_src_before_dst && diff >= 0));
 
     if (length < 8) {
diff --git a/programs/fileio.c b/programs/fileio.c
index 828878c6..98337672 100644
--- a/programs/fileio.c
+++ b/programs/fileio.c
@@ -319,6 +319,8 @@ struct FIO_prefs_s {
     /* Computation resources preferences */
     unsigned memLimit;
     int nbWorkers;
+
+    int excludeCompressedFiles;
 };
 
 
@@ -359,6 +361,7 @@ FIO_prefs_t* FIO_createPreferences(void)
     ret->srcSizeHint = 0;
     ret->testMode = 0;
     ret->literalCompressionMode = ZSTD_lcm_auto;
+    ret->excludeCompressedFiles = 0;
     return ret;
 }
 
@@ -402,6 +405,8 @@ void FIO_setNbWorkers(FIO_prefs_t* const prefs, int nbWorkers) {
     prefs->nbWorkers = nbWorkers;
 }
 
+void FIO_setExcludeCompressedFile(FIO_prefs_t* const prefs, int excludeCompressedFiles) { prefs->excludeCompressedFiles = excludeCompressedFiles; }
+
 void FIO_setBlockSize(FIO_prefs_t* const prefs, int blockSize) {
     if (blockSize && prefs->nbWorkers==0)
         DISPLAYLEVEL(2, "Setting block size is useless in single-thread mode \n");
@@ -520,7 +525,11 @@ static FILE* FIO_openSrcFile(const char* srcFileName)
         return NULL;
     }
 
-    if (!UTIL_isRegularFile(srcFileName) && !UTIL_isFIFO(srcFileName)) {
+    if (!UTIL_isRegularFile(srcFileName)
+#ifndef _MSC_VER
+        && !UTIL_isFIFO(srcFileName)
+#endif /* _MSC_VER */
+    ) {
         DISPLAYLEVEL(1, "zstd: %s is not a regular file -- ignored \n",
                         srcFileName);
         return NULL;
@@ -1425,6 +1434,21 @@ static int FIO_compressFilename_dstFile(FIO_prefs_t* const prefs,
     return result;
 }
 
+/* List used to compare file extensions (used with --exclude-compressed flag)
+* Different from the suffixList and should only apply to ZSTD compress operationResult
+*/
+static const char *compressedFileExtensions[] = {
+    ZSTD_EXTENSION,
+    TZSTD_EXTENSION,
+    GZ_EXTENSION,
+    TGZ_EXTENSION,
+    LZMA_EXTENSION,
+    XZ_EXTENSION,
+    TXZ_EXTENSION,
+    LZ4_EXTENSION,
+    TLZ4_EXTENSION,
+    NULL
+};
 
 /*! FIO_compressFilename_srcFile() :
  *  @return : 0 : compression completed correctly,
@@ -1451,6 +1475,15 @@ FIO_compressFilename_srcFile(FIO_prefs_t* const prefs,
         return 1;
     }
 
+    /* Check if "srcFile" is compressed. Only done if --exclude-compressed flag is used
+    * YES => ZSTD will skip compression of the file and will return 0.
+    * NO => ZSTD will resume with compress operation.
+    */
+    if (prefs->excludeCompressedFiles == 1 && UTIL_isCompressedFile(srcFileName, compressedFileExtensions)) {
+        DISPLAYLEVEL(4, "File is already compressed : %s \n", srcFileName);
+        return 0;
+    }
+
     ress.srcFile = FIO_openSrcFile(srcFileName);
     if (ress.srcFile == NULL) return 1;   /* srcFile could not be opened */
 
diff --git a/programs/fileio.h b/programs/fileio.h
index af2c5d9d..a7da089f 100644
--- a/programs/fileio.h
+++ b/programs/fileio.h
@@ -93,6 +93,7 @@ void FIO_setLiteralCompressionMode(
 
 void FIO_setNoProgress(unsigned noProgress);
 void FIO_setNotificationLevel(int level);
+void FIO_setExcludeCompressedFile(FIO_prefs_t* const prefs, int excludeCompressedFiles);
 
 /*-*************************************
 *  Single File functions
diff --git a/programs/util.c b/programs/util.c
index c09461ef..c9503e7f 100644
--- a/programs/util.c
+++ b/programs/util.c
@@ -152,6 +152,8 @@ int UTIL_isSameFile(const char* fName1, const char* fName2)
 #endif
 }
 
+#ifndef _MSC_VER
+/* Using this to distinguish named pipes */
 U32 UTIL_isFIFO(const char* infilename)
 {
 /* macro guards, as defined in : https://linux.die.net/man/2/lstat */
@@ -163,7 +165,7 @@ U32 UTIL_isFIFO(const char* infilename)
     (void)infilename;
     return 0;
 }
-
+#endif
 
 U32 UTIL_isLink(const char* infilename)
 {
@@ -525,6 +527,27 @@ int UTIL_prepareFileList(const char *dirName, char** bufStart, size_t* pos, char
 
 #endif /* #ifdef _WIN32 */
 
+int UTIL_isCompressedFile(const char *inputName, const char *extensionList[])
+{
+  const char* ext = UTIL_getFileExtension(inputName);
+  while(*extensionList!=NULL)
+  {
+    const int isCompressedExtension = strcmp(ext,*extensionList);
+    if(isCompressedExtension==0)
+      return 1;
+    ++extensionList;
+  }
+   return 0;
+}
+
+/*Utility function to get file extension from file */
+const char* UTIL_getFileExtension(const char* infilename)
+{
+   const char* extension = strrchr(infilename, '.');
+   if(!extension || extension==infilename) return "";
+   return extension;
+}
+
 /*
  * UTIL_createFileList - takes a list of files and directories (params: inputNames, inputNamesNb), scans directories,
  *                       and returns a new list of files (params: return value, allocatedBuffer, allocatedNamesNb).
diff --git a/programs/util.h b/programs/util.h
index d83dd187..d6c2ecf0 100644
--- a/programs/util.h
+++ b/programs/util.h
@@ -40,7 +40,6 @@ extern "C" {
 #include <time.h>         /* clock_t, clock, CLOCKS_PER_SEC, nanosleep */
 #include "mem.h"          /* U32, U64 */
 
-
 /*-************************************************************
 * Avoid fseek()'s 2GiB barrier with MSVC, macOS, *BSD, MinGW
 ***************************************************************/
@@ -135,8 +134,12 @@ U32 UTIL_isDirectory(const char* infilename);
 int UTIL_getFileStat(const char* infilename, stat_t* statbuf);
 int UTIL_isSameFile(const char* file1, const char* file2);
 int UTIL_compareStr(const void *p1, const void *p2);
+int UTIL_isCompressedFile(const char* infilename, const char *extensionList[]);
+const char* UTIL_getFileExtension(const char* infilename);
 
+#ifndef _MSC_VER
 U32 UTIL_isFIFO(const char* infilename);
+#endif
 U32 UTIL_isLink(const char* infilename);
 #define UTIL_FILESIZE_UNKNOWN  ((U64)(-1))
 U64 UTIL_getFileSize(const char* infilename);
diff --git a/programs/zstdcli.c b/programs/zstdcli.c
index 831143f1..a244b6c4 100644
--- a/programs/zstdcli.c
+++ b/programs/zstdcli.c
@@ -135,6 +135,7 @@ static int usage_advanced(const char* programName)
     DISPLAY( " -q     : suppress warnings; specify twice to suppress errors too\n");
     DISPLAY( " -c     : force write to standard output, even if it is the console\n");
     DISPLAY( " -l     : print information about zstd compressed files \n");
+    DISPLAY( "--exclude-compressed:  only compress files that are not previously compressed \n");
 #ifndef ZSTD_NOCOMPRESS
     DISPLAY( "--ultra : enable levels beyond %i, up to %i (requires more memory)\n", ZSTDCLI_CLEVEL_MAX, ZSTD_maxCLevel());
     DISPLAY( "--long[=#]: enable long distance matching with given window log (default: %u)\n", g_defaultMaxWindowLog);
@@ -710,7 +711,7 @@ int main(int argCount, const char* argv[])
                     if (!strcmp(argument, "--compress-literals")) { literalCompressionMode = ZSTD_lcm_huffman; continue; }
                     if (!strcmp(argument, "--no-compress-literals")) { literalCompressionMode = ZSTD_lcm_uncompressed; continue; }
                     if (!strcmp(argument, "--no-progress")) { FIO_setNoProgress(1); continue; }
-
+                    if (!strcmp(argument, "--exclude-compressed")) { FIO_setExcludeCompressedFile(prefs, 1); continue; }
                     /* long commands with arguments */
 #ifndef ZSTD_NODICT
                     if (longCommandWArg(&argument, "--train-cover")) {
@@ -1057,7 +1058,11 @@ int main(int argCount, const char* argv[])
     if (!followLinks) {
         unsigned u;
         for (u=0, fileNamesNb=0; u<filenameIdx; u++) {
-            if (UTIL_isLink(filenameTable[u]) && !UTIL_isFIFO(filenameTable[u])) {
+            if (UTIL_isLink(filenameTable[u])
+#ifndef _MSC_VER
+                && !UTIL_isFIFO(filenameTable[u])
+#endif /* _MSC_VER */
+            ) {
                 DISPLAYLEVEL(2, "Warning : %s is a symbolic link, ignoring\n", filenameTable[u]);
             } else {
                 filenameTable[fileNamesNb++] = filenameTable[u];
diff --git a/tests/fuzz/Makefile b/tests/fuzz/Makefile
index 83837e62..f66dadef 100644
--- a/tests/fuzz/Makefile
+++ b/tests/fuzz/Makefile
@@ -73,7 +73,8 @@ FUZZ_TARGETS :=       \
 	dictionary_round_trip \
 	dictionary_decompress \
 	zstd_frame_info \
-	simple_compress
+	simple_compress \
+	dictionary_loader
 
 all: $(FUZZ_TARGETS)
 
@@ -110,6 +111,9 @@ simple_compress: $(FUZZ_HEADERS) $(FUZZ_OBJ) simple_compress.o
 zstd_frame_info: $(FUZZ_HEADERS) $(FUZZ_OBJ) zstd_frame_info.o
 	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_OBJ) zstd_frame_info.o $(LIB_FUZZING_ENGINE) -o $@
 
+dictionary_loader: $(FUZZ_HEADERS) $(FUZZ_OBJ) dictionary_loader.o
+	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_OBJ) dictionary_loader.o $(LIB_FUZZING_ENGINE) -o $@
+
 libregression.a: $(FUZZ_HEADERS) $(PRGDIR)/util.h $(PRGDIR)/util.c regression_driver.o
 	$(AR) $(FUZZ_ARFLAGS) $@ regression_driver.o
 
diff --git a/tests/fuzz/dictionary_loader.c b/tests/fuzz/dictionary_loader.c
new file mode 100644
index 00000000..cb34f5d2
--- /dev/null
+++ b/tests/fuzz/dictionary_loader.c
@@ -0,0 +1,93 @@
+/*
+ * Copyright (c) 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ */
+
+/**
+ * This fuzz target makes sure that whenever a compression dictionary can be
+ * loaded, the data can be round tripped.
+ */
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "fuzz_helpers.h"
+#include "zstd_helpers.h"
+#include "fuzz_data_producer.h"
+
+/**
+ * Compresses the data and returns the compressed size or an error.
+ */
+static size_t compress(void* compressed, size_t compressedCapacity,
+                       void const* source, size_t sourceSize,
+                       void const* dict, size_t dictSize,
+                       ZSTD_dictLoadMethod_e dictLoadMethod,
+                       ZSTD_dictContentType_e dictContentType)
+{
+    ZSTD_CCtx* cctx = ZSTD_createCCtx();
+    FUZZ_ZASSERT(ZSTD_CCtx_loadDictionary_advanced(
+            cctx, dict, dictSize, dictLoadMethod, dictContentType));
+    size_t const compressedSize = ZSTD_compress2(
+            cctx, compressed, compressedCapacity, source, sourceSize);
+    ZSTD_freeCCtx(cctx);
+    return compressedSize;
+}
+
+static size_t decompress(void* result, size_t resultCapacity,
+                         void const* compressed, size_t compressedSize,
+                         void const* dict, size_t dictSize,
+                       ZSTD_dictLoadMethod_e dictLoadMethod,
+                         ZSTD_dictContentType_e dictContentType)
+{
+    ZSTD_DCtx* dctx = ZSTD_createDCtx();
+    FUZZ_ZASSERT(ZSTD_DCtx_loadDictionary_advanced(
+            dctx, dict, dictSize, dictLoadMethod, dictContentType));
+    size_t const resultSize = ZSTD_decompressDCtx(
+            dctx, result, resultCapacity, compressed, compressedSize);
+    FUZZ_ZASSERT(resultSize);
+    ZSTD_freeDCtx(dctx);
+    return resultSize;
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
+{
+    FUZZ_dataProducer_t *producer = FUZZ_dataProducer_create(src, size);
+    ZSTD_dictLoadMethod_e const dlm =
+    size = FUZZ_dataProducer_uint32Range(producer, 0, 1);
+    ZSTD_dictContentType_e const dct =
+            FUZZ_dataProducer_uint32Range(producer, 0, 2);
+    size = FUZZ_dataProducer_remainingBytes(producer);
+
+    DEBUGLOG(2, "Dict load method %d", dlm);
+    DEBUGLOG(2, "Dict content type %d", dct);
+    DEBUGLOG(2, "Dict size %u", (unsigned)size);
+
+    void* const rBuf = malloc(size);
+    FUZZ_ASSERT(rBuf);
+    size_t const cBufSize = ZSTD_compressBound(size);
+    void* const cBuf = malloc(cBufSize);
+    FUZZ_ASSERT(cBuf);
+
+    size_t const cSize =
+            compress(cBuf, cBufSize, src, size, src, size, dlm, dct);
+    /* compression failing is okay */
+    if (ZSTD_isError(cSize)) {
+      FUZZ_ASSERT_MSG(dct != ZSTD_dct_rawContent, "Raw must always succeed!");
+      goto out;
+    }
+    size_t const rSize =
+            decompress(rBuf, size, cBuf, cSize, src, size, dlm, dct);
+    FUZZ_ASSERT_MSG(rSize == size, "Incorrect regenerated size");
+    FUZZ_ASSERT_MSG(!memcmp(src, rBuf, size), "Corruption!");
+
+out:
+    free(cBuf);
+    free(rBuf);
+    FUZZ_dataProducer_free(producer);
+    return 0;
+}
diff --git a/tests/fuzz/fuzz.py b/tests/fuzz/fuzz.py
index 9df68df0..87f115af 100755
--- a/tests/fuzz/fuzz.py
+++ b/tests/fuzz/fuzz.py
@@ -27,6 +27,7 @@ def abs_join(a, *p):
 class InputType(object):
     RAW_DATA = 1
     COMPRESSED_DATA = 2
+    DICTIONARY_DATA = 3
 
 
 class FrameType(object):
@@ -54,6 +55,7 @@ TARGET_INFO = {
     'dictionary_decompress': TargetInfo(InputType.COMPRESSED_DATA),
     'zstd_frame_info': TargetInfo(InputType.COMPRESSED_DATA),
     'simple_compress': TargetInfo(InputType.RAW_DATA),
+    'dictionary_loader': TargetInfo(InputType.DICTIONARY_DATA),
 }
 TARGETS = list(TARGET_INFO.keys())
 ALL_TARGETS = TARGETS + ['all']
@@ -73,6 +75,7 @@ LIB_FUZZING_ENGINE = os.environ.get('LIB_FUZZING_ENGINE', 'libregression.a')
 AFL_FUZZ = os.environ.get('AFL_FUZZ', 'afl-fuzz')
 DECODECORPUS = os.environ.get('DECODECORPUS',
                               abs_join(FUZZ_DIR, '..', 'decodecorpus'))
+ZSTD = os.environ.get('ZSTD', abs_join(FUZZ_DIR, '..', '..', 'zstd'))
 
 # Sanitizer environment variables
 MSAN_EXTRA_CPPFLAGS = os.environ.get('MSAN_EXTRA_CPPFLAGS', '')
@@ -673,6 +676,11 @@ def gen_parser(args):
         default=DECODECORPUS,
         help="decodecorpus binary (default: $DECODECORPUS='{}')".format(
             DECODECORPUS))
+    parser.add_argument(
+        '--zstd',
+        type=str,
+        default=ZSTD,
+        help="zstd binary (default: $ZSTD='{}')".format(ZSTD))
     parser.add_argument(
         '--fuzz-rng-seed-size',
         type=int,
@@ -707,46 +715,66 @@ def gen(args):
         return 1
 
     seed = create(args.seed)
-    with tmpdir() as compressed:
-        with tmpdir() as decompressed:
-            cmd = [
-                args.decodecorpus,
-                '-n{}'.format(args.number),
-                '-p{}/'.format(compressed),
-                '-o{}'.format(decompressed),
+    with tmpdir() as compressed, tmpdir() as decompressed, tmpdir() as dict:
+        info = TARGET_INFO[args.TARGET]
+
+        if info.input_type == InputType.DICTIONARY_DATA:
+            number = max(args.number, 1000)
+        else:
+            number = args.number
+        cmd = [
+            args.decodecorpus,
+            '-n{}'.format(args.number),
+            '-p{}/'.format(compressed),
+            '-o{}'.format(decompressed),
+        ]
+
+        if info.frame_type == FrameType.BLOCK:
+            cmd += [
+                '--gen-blocks',
+                '--max-block-size-log={}'.format(min(args.max_size_log, 17))
             ]
+        else:
+            cmd += ['--max-content-size-log={}'.format(args.max_size_log)]
 
-            info = TARGET_INFO[args.TARGET]
-            if info.frame_type == FrameType.BLOCK:
-                cmd += [
-                    '--gen-blocks',
-                    '--max-block-size-log={}'.format(min(args.max_size_log, 17))
+        print(' '.join(cmd))
+        subprocess.check_call(cmd)
+
+        if info.input_type == InputType.RAW_DATA:
+            print('using decompressed data in {}'.format(decompressed))
+            samples = decompressed
+        elif info.input_type == InputType.COMPRESSED_DATA:
+            print('using compressed data in {}'.format(compressed))
+            samples = compressed
+        else:
+            assert info.input_type == InputType.DICTIONARY_DATA
+            print('making dictionary data from {}'.format(decompressed))
+            samples = dict
+            min_dict_size_log = 9
+            max_dict_size_log = max(min_dict_size_log + 1, args.max_size_log)
+            for dict_size_log in range(min_dict_size_log, max_dict_size_log):
+                dict_size = 1 << dict_size_log
+                cmd = [
+                    args.zstd,
+                    '--train',
+                    '-r', decompressed,
+                    '--maxdict={}'.format(dict_size),
+                    '-o', abs_join(dict, '{}.zstd-dict'.format(dict_size))
                 ]
-            else:
-                cmd += ['--max-content-size-log={}'.format(args.max_size_log)]
+                print(' '.join(cmd))
+                subprocess.check_call(cmd)
 
-            print(' '.join(cmd))
-            subprocess.check_call(cmd)
-
-            if info.input_type == InputType.RAW_DATA:
-                print('using decompressed data in {}'.format(decompressed))
-                samples = decompressed
-            else:
-                assert info.input_type == InputType.COMPRESSED_DATA
-                print('using compressed data in {}'.format(compressed))
-                samples = compressed
-
-            # Copy the samples over and prepend the RNG seeds
-            for name in os.listdir(samples):
-                samplename = abs_join(samples, name)
-                outname = abs_join(seed, name)
-                with open(samplename, 'rb') as sample:
-                    with open(outname, 'wb') as out:
-                        CHUNK_SIZE = 131072
+        # Copy the samples over and prepend the RNG seeds
+        for name in os.listdir(samples):
+            samplename = abs_join(samples, name)
+            outname = abs_join(seed, name)
+            with open(samplename, 'rb') as sample:
+                with open(outname, 'wb') as out:
+                    CHUNK_SIZE = 131072
+                    chunk = sample.read(CHUNK_SIZE)
+                    while len(chunk) > 0:
+                        out.write(chunk)
                         chunk = sample.read(CHUNK_SIZE)
-                        while len(chunk) > 0:
-                            out.write(chunk)
-                            chunk = sample.read(CHUNK_SIZE)
     return 0
 
 
diff --git a/tests/playTests.sh b/tests/playTests.sh
index 5f23ac55..05951ab2 100755
--- a/tests/playTests.sh
+++ b/tests/playTests.sh
@@ -215,6 +215,37 @@ $ZSTD tmp -c --compress-literals    -19      | $ZSTD -t
 $ZSTD -b --fast=1 -i0e1 tmp --compress-literals
 $ZSTD -b --fast=1 -i0e1 tmp --no-compress-literals
 
+println "test: --exclude-compressed flag"
+rm -rf precompressedFilterTestDir
+mkdir -p precompressedFilterTestDir
+./datagen $size > precompressedFilterTestDir/input.5
+./datagen $size > precompressedFilterTestDir/input.6
+$ZSTD --exclude-compressed --long --rm -r precompressedFilterTestDir
+sleep 5
+./datagen $size > precompressedFilterTestDir/input.7
+./datagen $size > precompressedFilterTestDir/input.8
+$ZSTD --exclude-compressed --long --rm -r precompressedFilterTestDir
+test ! -f precompressedFilterTestDir/input.5.zst.zst
+test ! -f precompressedFilterTestDir/input.6.zst.zst
+file1timestamp=`date -r precompressedFilterTestDir/input.5.zst +%s`
+file2timestamp=`date -r precompressedFilterTestDir/input.7.zst +%s`
+if [[ $file2timestamp -ge $file1timestamp ]]; then
+  println "Test is successful. input.5.zst is precompressed and therefore not compressed/modified again."
+else
+  println "Test is not successful"
+fi
+#File Extension check.
+./datagen $size > precompressedFilterTestDir/input.zstbar
+$ZSTD --exclude-compressed --long --rm -r precompressedFilterTestDir
+#ZSTD should compress input.zstbar
+test -f precompressedFilterTestDir/input.zstbar.zst
+#Check without the --exclude-compressed flag
+$ZSTD --long --rm -r precompressedFilterTestDir
+#Files should get compressed again without the --exclude-compressed flag.
+test -f precompressedFilterTestDir/input.5.zst.zst
+test -f precompressedFilterTestDir/input.6.zst.zst
+println "Test completed"
+
 println "test : file removal"
 $ZSTD -f --rm tmp
 test ! -f tmp  # tmp should no longer be present
@@ -1207,6 +1238,8 @@ test -f dictionary
 rm -f tmp* dictionary
 
 
+if [ "$isWindows" = false ] ; then
+
 println "\n===>  zstd fifo named pipe test "
 head -c 10 /dev/zero > tmp_original
 mkfifo named_pipe
@@ -1217,4 +1250,6 @@ $DIFF -s tmp_original tmp_decompressed
 rm -rf tmp*
 rm -rf named_pipe
 
+fi
+
 rm -f tmp*
diff --git a/zlibWrapper/Makefile b/zlibWrapper/Makefile
index f63291c9..6addb743 100644
--- a/zlibWrapper/Makefile
+++ b/zlibWrapper/Makefile
@@ -103,6 +103,7 @@ zstd_zlibwrapper.o: $(ZLIBWRAPPER_PATH)/zstd_zlibwrapper.c $(ZLIBWRAPPER_PATH)/z
 
 zstdTurnedOn_zlibwrapper.o: CPPFLAGS += -DZWRAP_USE_ZSTD=1
 zstdTurnedOn_zlibwrapper.o: $(ZLIBWRAPPER_PATH)/zstd_zlibwrapper.c $(ZLIBWRAPPER_PATH)/zstd_zlibwrapper.h
+	$(CC) $(CPPFLAGS) $(CFLAGS) $< -c -o $@
 
 $(ZSTDLIBDIR)/libzstd.a:
 	$(MAKE) -C $(ZSTDLIBDIR) libzstd.a