diff --git a/lib/common/zstd_internal.h b/lib/common/zstd_internal.h
index f7359646..7ea2ecc4 100644
--- a/lib/common/zstd_internal.h
+++ b/lib/common/zstd_internal.h
@@ -232,6 +232,8 @@ typedef struct ZSTD_CCtx_params_s {
     ZSTD_dictMode_e dictMode;
     U32 dictContentByRef;
 
+    /* Multithreading */
+    U32 nbThreads;
 
 } ZSTD_CCtx_params;
 
diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index 7802df50..e47ae9a1 100644
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -124,7 +124,7 @@ struct ZSTD_CCtx_s {
     size_t prefixSize;
 
     /* Multi-threading */
-    U32 nbThreads;
+//    U32 nbThreads;
     ZSTDMT_CCtx* mtctx;
 };
 
@@ -434,25 +434,25 @@ size_t ZSTD_CCtx_setParameter(ZSTD_CCtx* cctx, ZSTD_cParameter param, unsigned v
 #ifndef ZSTD_MULTITHREAD
         if (value > 1) return ERROR(parameter_unsupported);
 #endif
-        if ((value>1) && (cctx->nbThreads != value)) {
+        if ((value>1) && (cctx->requestedParams.nbThreads != value)) {
             if (cctx->staticSize)  /* MT not compatible with static alloc */
                 return ERROR(parameter_unsupported);
             ZSTDMT_freeCCtx(cctx->mtctx);
-            cctx->nbThreads = 1;
+            cctx->requestedParams.nbThreads = 1;
             cctx->mtctx = ZSTDMT_createCCtx_advanced(value, cctx->customMem);
             if (cctx->mtctx == NULL) return ERROR(memory_allocation);
         }
-        cctx->nbThreads = value;
+        cctx->requestedParams.nbThreads = value;
         return 0;
 
     case ZSTD_p_jobSize:
-        if (cctx->nbThreads <= 1) return ERROR(parameter_unsupported);
+        if (cctx->requestedParams.nbThreads <= 1) return ERROR(parameter_unsupported);
         assert(cctx->mtctx != NULL);
         return ZSTDMT_setMTCtxParameter(cctx->mtctx, ZSTDMT_p_sectionSize, value);
 
     case ZSTD_p_overlapSizeLog:
-        DEBUGLOG(5, " setting overlap with nbThreads == %u", cctx->nbThreads);
-        if (cctx->nbThreads <= 1) return ERROR(parameter_unsupported);
+        DEBUGLOG(5, " setting overlap with nbThreads == %u", cctx->requestedParams.nbThreads);
+        if (cctx->requestedParams.nbThreads <= 1) return ERROR(parameter_unsupported);
         assert(cctx->mtctx != NULL);
         return ZSTDMT_setMTCtxParameter(cctx->mtctx, ZSTDMT_p_overlapSectionLog, value);
 
@@ -549,7 +549,12 @@ size_t ZSTD_CCtxParam_setParameter(
         return 0;
 
     case ZSTD_p_nbThreads :
-        // TODO
+        if (value == 0) { return 0; }
+#ifndef ZSTD_MULTITHREAD
+        if (value > 1) return ERROR(parameter_unsupported);
+#endif
+        // Do checks when applying parameters to cctx.
+        params->nbThreads = value;
         return 0;
 
     case ZSTD_p_jobSize :
@@ -4224,8 +4229,8 @@ size_t ZSTD_compress_generic (ZSTD_CCtx* cctx,
         assert(prefix==NULL || cctx->cdict==NULL);   /* only one can be set */
 
 #ifdef ZSTD_MULTITHREAD
-        if (cctx->nbThreads > 1) {
-            DEBUGLOG(4, "call ZSTDMT_initCStream_internal as nbThreads=%u", cctx->nbThreads);
+        if (cctx->requestedParams.nbThreads > 1) {
+            DEBUGLOG(4, "call ZSTDMT_initCStream_internal as nbThreads=%u", cctx->requestedParams.nbThreads);
             CHECK_F( ZSTDMT_initCStream_internal(cctx->mtctx, prefix, prefixSize, cctx->cdict, params, cctx->pledgedSrcSizePlusOne-1) );
             cctx->streamStage = zcss_load;
         } else
@@ -4236,7 +4241,7 @@ size_t ZSTD_compress_generic (ZSTD_CCtx* cctx,
 
     /* compression stage */
 #ifdef ZSTD_MULTITHREAD
-    if (cctx->nbThreads > 1) {
+    if (cctx->requestedParams.nbThreads > 1) {
         size_t const flushMin = ZSTDMT_compressStream_generic(cctx->mtctx, output, input, endOp);
         DEBUGLOG(5, "ZSTDMT_compressStream_generic : %u", (U32)flushMin);
         if ( ZSTD_isError(flushMin)