diff --git a/lib/decompress/zstd_decompress.c b/lib/decompress/zstd_decompress.c
index 325f0b54dfc..4a97abe40e8 100644
--- a/lib/decompress/zstd_decompress.c
+++ b/lib/decompress/zstd_decompress.c
@@ -465,6 +465,9 @@ size_t ZSTD_getFrameHeader_advanced(ZSTD_FrameHeader* zfhPtr, const void* src, s
             assert(src != NULL);
             ZSTD_memcpy(hbuf, src, toCopy);
             if ( MEM_readLE32(hbuf) != ZSTD_MAGICNUMBER ) {
+#if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
+                if (ZSTD_isLegacy(hbuf, 4)) return minInputSize;   /* legacy frames are supported too */
+#endif
                 /* not a zstd frame : let's check if it's a skippable frame */
                 MEM_writeLE32(hbuf, ZSTD_MAGIC_SKIPPABLE_START);
                 ZSTD_memcpy(hbuf, src, toCopy);
@@ -2140,7 +2143,7 @@ size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inB
                 }
                 if (ZSTD_isError(hSize)) {
 #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
-                    U32 const legacyVersion = ZSTD_isLegacy(istart, iend-istart);
+                    U32 const legacyVersion = ZSTD_isLegacy(zds->headerBuffer, zds->lhSize);
                     if (legacyVersion) {
                         ZSTD_DDict const* const ddict = ZSTD_getDDict(zds);
                         const void* const dict = ddict ? ZSTD_DDict_dictContent(ddict) : NULL;
@@ -2152,7 +2155,13 @@ size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inB
                                     zds->previousLegacyVersion, legacyVersion,
                                     dict, dictSize), "");
                         zds->legacyVersion = zds->previousLegacyVersion = legacyVersion;
-                        {   size_t const hint = ZSTD_decompressLegacyStream(zds->legacyContext, legacyVersion, output, input);
+                        {   /* the frame header may have been buffered by previous calls : replay it first */
+                            ZSTD_inBuffer header;
+                            size_t hint;
+                            header.src = zds->headerBuffer; header.size = zds->lhSize; header.pos = 0;
+                            FORWARD_IF_ERROR(ZSTD_decompressLegacyStream(zds->legacyContext, legacyVersion, output, &header), "");
+                            input->pos = (size_t)(ip - (const char*)(input->src));
+                            hint = ZSTD_decompressLegacyStream(zds->legacyContext, legacyVersion, output, input);
                             if (hint==0) zds->streamStage = zdss_init;   /* or stay in stage zdss_loadHeader */
                             return hint;
                     }   }
diff --git a/tests/legacy.c b/tests/legacy.c
index 18a590f1d51..81bfd423f3e 100644
--- a/tests/legacy.c
+++ b/tests/legacy.c
@@ -156,8 +156,10 @@ static int testSimpleAPI(const char* compressed, size_t compressedSize,
 }
 
 
+/* @maxChunk : nb of bytes given to each ZSTD_decompressStream() call */
 static int testStreamingAPI(const char* compressed, size_t compressedSize,
-                            const char* expected, size_t expectedSize)
+                            const char* expected, size_t expectedSize,
+                            size_t maxChunk)
 {
     int error_code = 0;
     size_t const outBuffSize = ZSTD_DStreamOutSize();
@@ -168,7 +170,6 @@ static int testStreamingAPI(const char* compressed, size_t compressedSize,
     int needsInit = 1;
 
     input.src = compressed;
-    input.size = compressedSize;
 
     if (outBuff == NULL) {
         DISPLAY("ERROR: Could not allocate memory\n");
@@ -182,13 +183,16 @@ static int testStreamingAPI(const char* compressed, size_t compressedSize,
 
     while (1) {
         ZSTD_outBuffer output = {outBuff, outBuffSize, 0};
+        input.size = (compressedSize - input.pos > maxChunk) ? input.pos + maxChunk : compressedSize;
         if (needsInit) {
             size_t const ret = ZSTD_initDStream(stream);
             if (ZSTD_isError(ret)) {
                 DISPLAY("ERROR: ZSTD_initDStream: %s\n", ZSTD_getErrorName(ret));
                 error_code = 1;
                 break;
-        }   }
+            }
+            needsInit = 0;
+        }
 
         {   size_t const ret = ZSTD_decompressStream(stream, &output, &input);
             if (ZSTD_isError(ret)) {
@@ -212,7 +216,7 @@ static int testStreamingAPI(const char* compressed, size_t compressedSize,
             break;
         }
         outputPos += output.pos;
-        if (input.pos == input.size && output.pos < output.size) {
+        if (input.pos == compressedSize && output.pos < output.size) {
             break;
         }
     }
@@ -297,7 +301,10 @@ int main(void)
         /* all blocks being identical, the first @nbStreamFrames ones
          * are what the streaming subset must decode to */
         if (testStreamingAPI(streamable, streamableSize,
-                             expected, blockSize * nbStreamFrames)) break;
+                             expected, blockSize * nbStreamFrames, streamableSize)) break;
+        /* one byte at a time : frame headers arrive split across calls */
+        if (testStreamingAPI(streamable, streamableSize,
+                             expected, blockSize * nbStreamFrames, 1)) break;
         result = 0;
     } while (0);