diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index 94f4b5a2..e53ecc5f 100644
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -2235,7 +2235,7 @@ static size_t ZSTD_compress_generic (ZSTD_CCtx* cctx,
     BYTE* op = ostart;
     U32 const maxDist = 1 << cctx->params.cParams.windowLog;
 
-    if (cctx->params.fParams.checksumFlag)
+    if (cctx->params.fParams.checksumFlag && srcSize)
         XXH64_update(&cctx->xxhState, src, srcSize);
 
     while (remaining) {
@@ -2688,7 +2688,9 @@ ZSTD_CDict* ZSTD_createCDict_advanced(const void* dict, size_t dictSize, ZSTD_pa
             return NULL;
         }
 
-        memcpy(dictContent, dict, dictSize);
+        if (dictSize) {
+            memcpy(dictContent, dict, dictSize);
+        }
         {   size_t const errorCode = ZSTD_compressBegin_advanced(cctx, dictContent, dictSize, params, 0);
             if (ZSTD_isError(errorCode)) {
                 ZSTD_free(dictContent, customMem);
diff --git a/lib/decompress/zstd_decompress.c b/lib/decompress/zstd_decompress.c
index d157e005..bb4336ff 100644
--- a/lib/decompress/zstd_decompress.c
+++ b/lib/decompress/zstd_decompress.c
@@ -1402,7 +1402,9 @@ ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize, ZSTD_cu
             return NULL;
         }
 
-        memcpy(dictContent, dict, dictSize);
+        if (dictSize) {
+            memcpy(dictContent, dict, dictSize);
+        }
         {   size_t const errorCode = ZSTD_decompressBegin_usingDict(dctx, dictContent, dictSize);
             if (ZSTD_isError(errorCode)) {
                 ZSTD_free(dictContent, customMem);