diff --git a/lib/decompress/zstd_decompress.c b/lib/decompress/zstd_decompress.c
index 325f0b54dfc..0fb5eeffbba 100644
--- a/lib/decompress/zstd_decompress.c
+++ b/lib/decompress/zstd_decompress.c
@@ -1947,6 +1947,10 @@ size_t ZSTD_DCtx_reset(ZSTD_DCtx* dctx, ZSTD_ResetDirective reset)
 {
     if ( (reset == ZSTD_reset_session_only)
       || (reset == ZSTD_reset_session_and_parameters) ) {
+        /* A prefix is only used once : if a frame was started, it is abandoned now,
+         * so the prefix must not leak into the next frame */
+        if (dctx->streamStage != zdss_init && dctx->dictUses == ZSTD_use_once)
+            ZSTD_clearDict(dctx);
         dctx->streamStage = zdss_init;
         dctx->noForwardProgress = 0;
         dctx->isFrameDecompression = 1;
diff --git a/tests/zstreamtest.c b/tests/zstreamtest.c
index 88a20a3e270..39a21a434b8 100644
--- a/tests/zstreamtest.c
+++ b/tests/zstreamtest.c
@@ -1406,6 +1406,39 @@ static int basicUnitTests(U32 seed, double compressibility, int bigTests)
         DISPLAYLEVEL(3, "OK (%s)\n", ZSTD_getErrorName(r));
     }
 
+    DISPLAYLEVEL(3, "test%3i : prefix is dropped by session reset after a rejected frame header : ", testNb++);
+    {   BYTE const badHeader[6] = { 0x28, 0xB5, 0x2F, 0xFD, 0x08, 0x00 };  /* reserved bit set */
+        CHECK_Z( ZSTD_DCtx_refPrefix(zd, dictionary.start, dictionary.filled) );
+        outBuff.dst = decodedBuffer;
+        outBuff.size = CNBufferSize;
+        outBuff.pos = 0;
+        inBuff.src = badHeader;
+        inBuff.size = sizeof(badHeader);
+        inBuff.pos = 0;
+        if (!ZSTD_isError(ZSTD_decompressStream(zd, &outBuff, &inBuff))) goto _output_error;
+        CHECK_Z( ZSTD_DCtx_reset(zd, ZSTD_reset_session_only) );
+        outBuff.pos = 0;
+        inBuff.src = compressedBuffer;
+        inBuff.size = cSize;
+        inBuff.pos = 0;
+        if (!ZSTD_isError(ZSTD_decompressStream(zd, &outBuff, &inBuff))) goto _output_error;  /* prefix must be gone */
+        CHECK_Z( ZSTD_DCtx_reset(zd, ZSTD_reset_session_only) );
+    }
+    DISPLAYLEVEL(3, "OK \n");
+
+    DISPLAYLEVEL(3, "test%3i : prefix survives session reset before any input : ", testNb++);
+    CHECK_Z( ZSTD_DCtx_refPrefix(zd, dictionary.start, dictionary.filled) );
+    CHECK_Z( ZSTD_DCtx_reset(zd, ZSTD_reset_session_only) );
+    outBuff.dst = decodedBuffer;
+    outBuff.size = CNBufferSize;
+    outBuff.pos = 0;
+    inBuff.src = compressedBuffer;
+    inBuff.size = cSize;
+    inBuff.pos = 0;
+    CHECK_Z( ZSTD_decompressStream(zd, &outBuff, &inBuff) );
+    if (outBuff.pos != CNBufferSize) goto _output_error;  /* must regenerate whole input */
+    DISPLAYLEVEL(3, "OK \n");
+
     DISPLAYLEVEL(3, "test%3i : compress again with ZSTD_compressStream2 : ", testNb++);
     outBuff.dst = compressedBuffer;
     outBuff.size = compressedBufferSize;