diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index 2ff1fa209..0fa2e6e2d 100644
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -1577,7 +1577,7 @@ static size_t ZSTD_estimateCCtxSize_usingCCtxParams_internal(
         size_t maxBlockSize)
 {
     size_t const windowSize = (size_t) BOUNDED(1ULL, 1ULL << cParams->windowLog, pledgedSrcSize);
-    size_t const blockSize = MIN(maxBlockSize, windowSize);
+    size_t const blockSize = MIN(ZSTD_resolveMaxBlockSize(maxBlockSize), windowSize);
     size_t const maxNbSeq = ZSTD_maxNbSeq(blockSize, cParams->minMatch, useExternalMatchFinder);
     size_t const tokenSpace = ZSTD_cwksp_alloc_size(WILDCOPY_OVERLENGTH + blockSize)
                             + ZSTD_cwksp_aligned_alloc_size(maxNbSeq * sizeof(seqDef))
@@ -1679,7 +1679,7 @@ size_t ZSTD_estimateCStreamSize_usingCCtxParams(const ZSTD_CCtx_params* params)
     RETURN_ERROR_IF(params->nbWorkers > 0, GENERIC, "Estimate CCtx size is supported for single-threaded compression only.");
     {   ZSTD_compressionParameters const cParams =
                 ZSTD_getCParamsFromCCtxParams(params, ZSTD_CONTENTSIZE_UNKNOWN, 0, ZSTD_cpm_noAttachDict);
-        size_t const blockSize = MIN(params->maxBlockSize, (size_t)1 << cParams.windowLog);
+        size_t const blockSize = MIN(ZSTD_resolveMaxBlockSize(params->maxBlockSize), (size_t)1 << cParams.windowLog);
         size_t const inBuffSize = (params->inBufferMode == ZSTD_bm_buffered)
                 ? ((size_t)1 << cParams.windowLog) + blockSize
                 : 0;
@@ -1964,6 +1964,7 @@ static size_t ZSTD_resetCCtx_internal(ZSTD_CCtx* zc,
     assert(params->useRowMatchFinder != ZSTD_ps_auto);
     assert(params->useBlockSplitter != ZSTD_ps_auto);
     assert(params->ldmParams.enableLdm != ZSTD_ps_auto);
+    assert(params->maxBlockSize != 0);
     if (params->ldmParams.enableLdm == ZSTD_ps_enable) {
         /* Adjust long distance matching parameters */
         ZSTD_ldm_adjustParameters(&zc->appliedParams.ldmParams, &params->cParams);
diff --git a/tests/fuzzer.c b/tests/fuzzer.c
index 3ad8ced5e..ef1fef14f 100644
--- a/tests/fuzzer.c
+++ b/tests/fuzzer.c
@@ -1725,6 +1725,94 @@ static int basicUnitTests(U32 const seed, double compressibility)
                 if (!ZSTD_isError(r)) goto _output_error;
             }
             DISPLAYLEVEL(3, "OK \n");
+
+            DISPLAYLEVEL(3, "test%3i : test estimation functions with default cctx params : ", testNb++);
+            {
+                // Test ZSTD_estimateCCtxSize_usingCCtxParams
+                {
+                    ZSTD_CCtx_params* params = ZSTD_createCCtxParams();
+                    size_t const cctxSizeDefault = ZSTD_estimateCCtxSize_usingCCtxParams(params);
+                    staticCCtx = ZSTD_initStaticCCtx(staticCCtxBuffer, cctxSizeDefault);
+                    CHECK_VAR(cSize, ZSTD_compressCCtx(staticCCtx,
+                                    compressedBuffer, compressedBufferSize,
+                                    CNBuffer, CNBuffSize, 3));
+
+                    {
+                        size_t const r = ZSTD_decompressDCtx(staticDCtx,
+                                                    decodedBuffer, CNBuffSize,
+                                                    compressedBuffer, cSize);
+                                                                        if (r != CNBuffSize) goto _output_error;
+                        if (memcmp(decodedBuffer, CNBuffer, CNBuffSize)) goto _output_error;
+                    }
+                    ZSTD_freeCCtxParams(params);
+                }
+
+                // Test ZSTD_estimateCStreamSize_usingCCtxParams
+                  {
+                    ZSTD_CCtx_params* params = ZSTD_createCCtxParams();
+                    size_t const cctxSizeDefault = ZSTD_estimateCStreamSize_usingCCtxParams(params);
+                    staticCCtx = ZSTD_initStaticCCtx(staticCCtxBuffer, cctxSizeDefault);
+                    CHECK_VAR(cSize, ZSTD_compressCCtx(staticCCtx,
+                                    compressedBuffer, compressedBufferSize,
+                                    CNBuffer, CNBuffSize, 3) );
+
+                    {
+                        size_t const r = ZSTD_decompressDCtx(staticDCtx,
+                                                    decodedBuffer, CNBuffSize,
+                                                    compressedBuffer, cSize);
+                                                                        if (r != CNBuffSize) goto _output_error;
+                        if (memcmp(decodedBuffer, CNBuffer, CNBuffSize)) goto _output_error;
+                    }
+                    ZSTD_freeCCtxParams(params);
+                }
+            }
+            DISPLAYLEVEL(3, "OK \n");
+
+            DISPLAYLEVEL(3, "test%3i : test estimation functions with maxBlockSize = 0 : ", testNb++);
+            {
+                // Test ZSTD_estimateCCtxSize_usingCCtxParams
+                {
+                    ZSTD_CCtx_params* params = ZSTD_createCCtxParams();
+                    size_t cctxSizeDefault;
+                    CHECK_Z(ZSTD_CCtxParams_setParameter(params, ZSTD_c_maxBlockSize, 0));
+                    cctxSizeDefault = ZSTD_estimateCCtxSize_usingCCtxParams(params);
+                    staticCCtx = ZSTD_initStaticCCtx(staticCCtxBuffer, cctxSizeDefault);
+                    CHECK_VAR(cSize, ZSTD_compressCCtx(staticCCtx,
+                                    compressedBuffer, compressedBufferSize,
+                                    CNBuffer, CNBuffSize, 3) );
+
+                    {
+                        size_t const r = ZSTD_decompressDCtx(staticDCtx,
+                                                    decodedBuffer, CNBuffSize,
+                                                    compressedBuffer, cSize);
+                                                                        if (r != CNBuffSize) goto _output_error;
+                        if (memcmp(decodedBuffer, CNBuffer, CNBuffSize)) goto _output_error;
+                    }
+                    ZSTD_freeCCtxParams(params);
+                }
+
+                // Test ZSTD_estimateCStreamSize_usingCCtxParams
+                  {
+                    ZSTD_CCtx_params* params = ZSTD_createCCtxParams();
+                    size_t cctxSizeDefault;
+                    CHECK_Z(ZSTD_CCtxParams_setParameter(params, ZSTD_c_maxBlockSize, 0));
+                    cctxSizeDefault = ZSTD_estimateCStreamSize_usingCCtxParams(params);
+                    staticCCtx = ZSTD_initStaticCCtx(staticCCtxBuffer, cctxSizeDefault);
+                    CHECK_VAR(cSize, ZSTD_compressCCtx(staticCCtx,
+                                    compressedBuffer, compressedBufferSize,
+                                    CNBuffer, CNBuffSize, 3) );
+
+                    {
+                        size_t const r = ZSTD_decompressDCtx(staticDCtx,
+                                                    decodedBuffer, CNBuffSize,
+                                                    compressedBuffer, cSize);
+                                                                        if (r != CNBuffSize) goto _output_error;
+                        if (memcmp(decodedBuffer, CNBuffer, CNBuffSize)) goto _output_error;
+                    }
+                    ZSTD_freeCCtxParams(params);
+                }
+            }
+            DISPLAYLEVEL(3, "OK \n");
         }
         free(staticCCtxBuffer);
         free(staticDCtxBuffer);