diff --git a/iguana/iguana777.h b/iguana/iguana777.h
index 54b7758cf..a41935219 100755
--- a/iguana/iguana777.h
+++ b/iguana/iguana777.h
@@ -1074,6 +1074,10 @@ void calc_scrypthash(uint32_t *hash,void *data);
 int32_t iguana_rwvarstr(int32_t rwflag,uint8_t *serialized,int32_t maxlen,char *endianedp);
 bits256 bitcoin_sharedsecret(void *ctx,bits256 privkey,uint8_t *pubkey,int32_t plen);
 int32_t iguana_blockhdrsize(char *symbol,uint8_t zcash,uint8_t auxpow);//,uint8_t *serialized,int32_t maxlen);
+int32_t iguana_blockROsize(uint8_t zcash);
+void *iguana_blockzcopyRO(uint8_t zcash,struct iguana_blockRO *dest,int32_t desti,struct iguana_blockRO *src,int32_t srci);
+void iguana_blockzcopy(uint8_t zcash,struct iguana_block *dest,struct iguana_block *src);
+int32_t iguana_blocksizecheck(char *debugstr,uint8_t zcash,struct iguana_block *block);
 
 extern int32_t HDRnet,netBLOCKS;
 
diff --git a/iguana/iguana_blocks.c b/iguana/iguana_blocks.c
index 3bcc536c6..21b98a07b 100755
--- a/iguana/iguana_blocks.c
+++ b/iguana/iguana_blocks.c
@@ -96,7 +96,9 @@ void iguana_blockcopy(uint8_t zcash,uint8_t auxpow,struct iguana_info *coin,stru
     }
     else
     {
-        if ( block->RO.allocsize != origblock->RO.allocsize || block->RO.allocsize != sizeof(*block) + sizeof(*block->zRO) )
+        iguana_blocksizecheck("blockcopy dest",coin->chain->zcash,block);
+        iguana_blocksizecheck("blockcopy src",coin->chain->zcash,origblock);
+        if ( block->RO.allocsize != origblock->RO.allocsize )
             printf("missing space for zcash block.%d origblock.%d\n",block->RO.allocsize,origblock->RO.allocsize);
         else
         {
@@ -210,6 +212,7 @@ struct iguana_block *iguana_blockhashset(char *debugstr,struct iguana_info *coin
         block = calloc(1,size);
         block->RO.hash2 = hash2;
         block->RO.allocsize = size;
+        iguana_blocksizecheck("blockhashset",coin->chain->zcash,block);
         block->hh.itemind = height, block->height = -1;
         HASH_ADD(hh,coin->blocks.hash,RO.hash2,sizeof(hash2),block);
         block->hh.next = block->hh.prev = 0;
@@ -277,6 +280,50 @@ struct iguana_block *iguana_blockptr(char *debugstr,struct iguana_info *coin,int
     return(0);
 }
 
+int32_t iguana_blocksizecheck(char *debugstr,uint8_t zcash,struct iguana_block *block)
+{
+    int32_t bsize = zcash != 0 ? sizeof(struct iguana_zblock) : sizeof(struct iguana_block);
+    if ( block->RO.allocsize != bsize )
+    {
+        if ( block->RO.allocsize == 0 || block->RO.allocsize < bsize )
+        {
+            printf("%s block validate warning: mismatched size %d vs %d\n",debugstr,block->RO.allocsize,bsize);
+            block->RO.allocsize = bsize;
+        } else return(-1);
+        return(bsize);
+    }
+    return(0);
+}
+
+int32_t iguana_blockROsize(uint8_t zcash)
+{
+    return((int32_t)(sizeof(struct iguana_blockRO) + zcash*sizeof(struct iguana_msgblockhdr_zcash)));
+}
+
+void *iguana_blockzcopyRO(uint8_t zcash,struct iguana_blockRO *dest,int32_t desti,struct iguana_blockRO *src,int32_t srci)
+{
+    int32_t bROsize = iguana_blockROsize(zcash);
+    dest = (void *)((long)dest + desti*bROsize);
+    src = (void *)((long)src + srci*bROsize);
+    memcpy(dest,src,bROsize);
+    return(src);
+}
+
+void iguana_blockzcopy(uint8_t zcash,struct iguana_block *dest,struct iguana_block *src)
+{
+    iguana_blocksizecheck("blockcopy dest",zcash,dest);
+    iguana_blocksizecheck("blockcopy src",zcash,src);
+    if ( zcash == 0 )
+        *dest = *src;
+    else
+    {
+        if ( src->RO.allocsize != sizeof(struct iguana_zblock) )
+            printf("warning: iguana_blockcopy src size %d vs %d\n",src->RO.allocsize,(int32_t)sizeof(struct iguana_zblock));
+        *(struct iguana_zblock *)dest = *(struct iguana_zblock *)src;
+        dest->RO.allocsize = sizeof(struct iguana_zblock);
+    }
+}
+
 int32_t iguana_blockvalidate(struct iguana_info *coin,int32_t *validp,struct iguana_block *block,int32_t dispflag)
 {
     bits256 hash2; uint8_t serialized[sizeof(struct iguana_msgblock) + 4096];
@@ -284,8 +331,7 @@ int32_t iguana_blockvalidate(struct iguana_info *coin,int32_t *validp,struct igu
     iguana_serialize_block(coin->chain,&hash2,serialized,block);
     *validp = (memcmp(hash2.bytes,block->RO.hash2.bytes,sizeof(hash2)) == 0);
     block->valid = *validp;
-    if ( block->RO.allocsize == 0 )
-        block->RO.allocsize = coin->chain->zcash != 0 ? sizeof(*block) : sizeof(struct iguana_zblock);
+    iguana_blocksizecheck("blockvalidate",coin->chain->zcash,block);
     char str[65]; char str2[65];
     if ( *validp == 0 )
     {
@@ -387,6 +433,7 @@ int32_t iguana_walkchain(struct iguana_info *coin,int32_t skipflag)
         }
         else if ( block->height >= 0 && block->height != height )
             printf("walkchain height mismatch %d vs %d\n",block->height,height);
+        iguana_blocksizecheck("walkchain",coin->chain->zcash,block);
         if ( bits256_nonz(iguana_blockhash(coin,height)) != 0 && bits256_cmp(iguana_blockhash(coin,height),block->RO.hash2) != 0 )
         {
             printf("walk error blockhash error at %d %s\n",height,bits256_str(str,iguana_blockhash(coin,height)));
@@ -451,7 +498,6 @@ struct iguana_block *iguana_fastlink(struct iguana_info *coin,int32_t hwmheight)
         coin->blocks.maxblocks = (block->height + 1);
         if ( coin->blocks.maxblocks > coin->longestchain )
             coin->longestchain = coin->blocks.maxblocks;
-        memcpy(&coin->blocks.hwmchain,block,block->RO.allocsize);
         block->valid = block->mainchain = 1;
         block->hdrsi = hdrsi, block->bundlei = bundlei;
         block->height = height;
@@ -487,15 +533,13 @@ struct iguana_block *_iguana_chainlink(struct iguana_info *coin,struct iguana_bl
     bits256 *hash2p=0; double prevPoW = 0.; struct iguana_bundle *bp;
     if ( newblock == 0 )
         return(0);
-    if ( newblock->RO.allocsize == 0 )
-        newblock->RO.allocsize = coin->chain->zcash != 0 ? sizeof(*newblock) : sizeof(struct iguana_zblock);
+    iguana_blocksizecheck("chainlink new",coin->chain->zcash,newblock);
     hwmchain = (struct iguana_block *)&coin->blocks.hwmchain;
     if ( 0 && hwmchain->height > 0 && ((bp= coin->current) == 0 || hwmchain->height/coin->chain->bundlesize > bp->hdrsi+0*bp->isRT) )
         return(0);
     if ( (block= iguana_blockfind("chainlink",coin,newblock->RO.hash2)) != 0 )
     {
-        if ( block->RO.allocsize == 0 )
-            block->RO.allocsize = coin->chain->zcash != 0 ? sizeof(*newblock) : sizeof(struct iguana_zblock);
+        iguana_blocksizecheck("chainlink",coin->chain->zcash,block);
         if ( memcmp(coin->chain->genesis_hashdata,block->RO.hash2.bytes,sizeof(bits256)) == 0 )
             block->PoW = PoW_from_compact(block->RO.bits,coin->chain->unitval), height = 0;
         else if ( (prev= iguana_blockfind("chainprev",coin,block->RO.prev_block)) != 0 )
diff --git a/iguana/iguana_init.c b/iguana/iguana_init.c
index 4871e415d..cfb53143e 100755
--- a/iguana/iguana_init.c
+++ b/iguana/iguana_init.c
@@ -86,7 +86,7 @@ bits256 iguana_genesis(struct iguana_info *coin,struct iguana_chain *chain)
     struct iguana_block *block,*ptr; struct iguana_msgblock msg; bits256 hash2; char str[65],str2[65]; uint8_t buf[8192],blockspace[sizeof(*block)+sizeof(*block->zRO)]; int32_t height,auxback;
     block = (void *)blockspace;
     memset(block,0,sizeof(blockspace));
-    block->RO.allocsize = (int32_t)(sizeof(*block) + coin->chain->zcash*sizeof(*block->zRO));
+    iguana_blocksizecheck("genesis",coin->chain->zcash,block);
     if ( chain->genesis_hex == 0 )
     {
         printf("no genesis_hex for %s\n",coin->symbol);
@@ -117,12 +117,13 @@ bits256 iguana_genesis(struct iguana_info *coin,struct iguana_chain *chain)
     if ( (ptr= iguana_blockhashset("genesis0",coin,0,hash2,1)) != 0 )
     {
         iguana_blockcopy(coin->chain->zcash,coin->chain->auxpow,coin,ptr,block);
+        iguana_blocksizecheck("genesis ptr",coin->chain->zcash,ptr);
         ptr->mainchain = 1;
         ptr->height = 0;
         //coin->blocks.RO[0] = block.RO;
         if ( (height= iguana_chainextend(coin,ptr)) == 0 )
         {
-            memcpy(block,ptr,block->RO.allocsize);
+            iguana_blockzcopy(coin->chain->zcash,block,ptr);
             printf("size.%d genesis block PoW %f ptr %f\n",block->RO.allocsize,block->PoW,ptr->PoW);
             coin->blocks.recvblocks = coin->blocks.issuedblocks = 1;
         }
diff --git a/iguana/iguana_msg.c b/iguana/iguana_msg.c
index 9022276fe..c4d77f290 100755
--- a/iguana/iguana_msg.c
+++ b/iguana/iguana_msg.c
@@ -217,7 +217,7 @@ int32_t iguana_serialize_block(struct iguana_chain *chain,bits256 *hash2p,uint8_
         msg.H.nonce = block->RO.nonce;
     else
     {
-        if ( block->RO.allocsize == sizeof(*block)+sizeof(*block->zRO) )
+        if ( block->RO.allocsize == sizeof(struct iguana_zblock) ) 
         {
             msg.zH.bignonce = block->zRO[0].bignonce;
             msg.zH.numelements = ZCASH_SOLUTION_ELEMENTS;
diff --git a/iguana/iguana_ramchain.c b/iguana/iguana_ramchain.c
index d871b58e6..7844c4dc8 100755
--- a/iguana/iguana_ramchain.c
+++ b/iguana/iguana_ramchain.c
@@ -788,7 +788,7 @@ int32_t iguana_ramchain_prefetch(struct iguana_info *coin,struct iguana_ramchain
 int64_t _iguana_rdata_action(char *fname,FILE *fp,bits256 lhashes[IGUANA_NUMLHASHES],void *destptr,uint64_t fpos,uint32_t expanded,uint32_t numtxids,uint32_t numunspents,uint32_t numspends,uint32_t numpkinds,uint32_t numexternaltxids,uint32_t scriptspace,uint32_t txsparsebits,uint64_t numtxsparse,uint32_t pksparsebits,uint64_t numpksparse,uint64_t srcsize,RAMCHAIN_FUNC,int32_t numblocks,uint8_t zcash)
 {
 #define RAMCHAIN_LARG(ind) ((lhashes == 0) ? 0 : lhashes[ind].bytes)
-    FILE *fparg = 0; int32_t bROsize,iter; uint64_t txbits,pkbits,offset = 0; struct iguana_ramchaindata *rdata = destptr;
+    FILE *fparg = 0; int32_t iter; uint64_t txbits,pkbits,offset = 0; struct iguana_ramchaindata *rdata = destptr;
     if ( expanded != 0 )
     {
         if( txsparsebits == 0 || numtxsparse == 0 )
@@ -823,9 +823,8 @@ int64_t _iguana_rdata_action(char *fname,FILE *fp,bits256 lhashes[IGUANA_NUMLHAS
             continue;
         }
         offset = sizeof(struct iguana_ramchaindata);
-        bROsize = (int32_t)(sizeof(struct iguana_blockRO) + zcash*sizeof(struct iguana_msgblockhdr_zcash));
         //printf("bROsize.%d\n",bROsize);
-        B = iguana_ramchain_offset(fname,rdata,RAMCHAIN_LARG(IGUANA_LHASH_BLOCKS),fparg,fpos,B,&offset,(bROsize * numblocks),srcsize);
+        B = iguana_ramchain_offset(fname,rdata,RAMCHAIN_LARG(IGUANA_LHASH_BLOCKS),fparg,fpos,B,&offset,(iguana_blockROsize(zcash) * numblocks),srcsize);
         T = iguana_ramchain_offset(fname,rdata,RAMCHAIN_LARG(IGUANA_LHASH_TXIDS),fparg,fpos,T,&offset,(sizeof(struct iguana_txid) * numtxids),srcsize);
         if ( expanded != 0 )
         {
@@ -1473,18 +1472,19 @@ struct iguana_ramchain *_iguana_ramchain_map(struct iguana_info *coin,char *fnam
         }
         if ( B != 0 && bp != 0 )
         {
-            int32_t bROsize = (int32_t)(sizeof(struct iguana_blockRO) + coin->chain->zcash*sizeof(struct iguana_msgblockhdr_zcash));
             for (i=0; i<bp->n; i++)
             {
-                bRO = (void *)((long)B + i*bROsize);
                 if ( bp->blocks[i] == 0 &&  (bp->blocks[i]= iguana_blockhashset("mapchain",coin,-1,bRO->hash2,1)) == 0 )
                 {
                     printf("Error getting blockptr\n");
                     return(0);
                 }
-                memcpy(&bp->blocks[i]->RO,bRO,bROsize);//coin->blocks.RO[bp->bundleheight + i];
-                //coin->blocks.RO[bp->bundleheight+i] = B[i];
-                bp->hashes[i] = bRO->hash2;
+                if ( (bRO= iguana_blockzcopyRO(zcash,&bp->blocks[i]->RO,0,B,i)) != 0 )
+                {
+                    //memcpy(&bp->blocks[i]->RO,bRO,bROsize);//coin->blocks.RO[bp->bundleheight + i];
+                    //coin->blocks.RO[bp->bundleheight+i] = B[i];
+                    bp->hashes[i] = bRO->hash2;
+                }
             }
         }
         //printf("iguana_ramchain_map.(%s) size %ld vs %ld vs filesize.%ld numblocks.%d expanded.%d fpos.%d sum %ld\n",fname,(long)iguana_ramchain_size(RAMCHAIN_ARG,ramchain->numblocks,ramchain->H.data->scriptspace),(long)ramchain->H.data->allocsize,(long)filesize,ramchain->numblocks,expanded,(int32_t)fpos,(long)(fpos+ramchain->H.data->allocsize));
@@ -1945,8 +1945,7 @@ long iguana_ramchain_data(struct iguana_info *coin,struct iguana_peer *addr,stru
     {
         if ( (err= iguana_ramchain_verify(coin,ramchain)) == 0 )
         {
-            int32_t bROsize = (int32_t)(sizeof(struct iguana_blockRO) + coin->chain->zcash*sizeof(struct iguana_msgblockhdr_zcash));
-            memcpy(B,&block->RO,bROsize);
+            iguana_blockzcopyRO(coin->chain->zcash,B,0,&block->RO,0);
             ramchain->H.data->scriptspace = ramchain->H.scriptoffset = scriptspace;
             ramchain->H.data->stackspace = ramchain->H.stacksize = stackspace;
             if ( (fpos= (int32_t)iguana_ramchain_save(coin,RAMCHAIN_ARG,addr_ipbits,block->RO.hash2,block->RO.prev_block,bundlei,0,coin->chain->zcash)) >= 0 )
@@ -2293,10 +2292,9 @@ int32_t iguana_ramchain_expandedsave(struct iguana_info *coin,RAMCHAIN_FUNC,stru
 struct iguana_ramchain *iguana_bundleload(struct iguana_info *coin,struct iguana_ramchain *ramchain,struct iguana_bundle *bp,int32_t extraflag)
 {
     static const bits256 zero;
-    struct iguana_blockRO *B; struct iguana_txid *T; int32_t i,bROsize,firsti = 1; char fname[512];
+    struct iguana_blockRO *B; struct iguana_txid *T; int32_t i,firsti = 1; char fname[512];
     struct iguana_block *block,*prev,*prev2; struct iguana_ramchain *mapchain;
     memset(ramchain,0,sizeof(*ramchain));
-    bROsize = (int32_t)(sizeof(struct iguana_blockRO) + coin->chain->zcash*sizeof(struct iguana_msgblockhdr_zcash));
     if ( (mapchain= iguana_ramchain_map(coin,fname,bp,bp->n,ramchain,0,0,bp->hashes[0],zero,0,0,extraflag,1)) != 0 )
     {
         iguana_ramchain_link(mapchain,bp->hashes[0],bp->hdrsi,bp->bundleheight,0,bp->n,firsti,1);
@@ -2320,12 +2318,10 @@ struct iguana_ramchain *iguana_bundleload(struct iguana_info *coin,struct iguana
                 block->hdrsi = bp->hdrsi;
                 block->bundlei = i;
                 block->fpipbits = (uint32_t)calc_ipbits("127.0.0.1");
-                memcpy(&block->RO,(void *)((long)B + i*bROsize),bROsize);
+                iguana_blockzcopyRO(coin->chain->zcash,&block->RO,0,B,i);
                 //printf("%x ",(int32_t)B[i].hash2.ulongs[3]);
                 iguana_hash2set(coin,"bundleload",bp,i,block->RO.hash2);
                 bp->blocks[i] = block;
-                //if ( bits256_nonz(bp->hashes[i]) == 0 )
-                //    bp->hashes[i] = bRO->hash2;
                 if ( (prev= block->hh.prev) != 0 )
                     prev2 = prev->hh.prev;
                 if ( prev2 != 0 && prev != 0 && strcmp(coin->symbol,"BTCD") == 0 && bp->bundleheight > 20000 && prev != 0 && iguana_targetbits(coin,block,prev,prev2,1,coin->chain->targetspacing,coin->chain->targettimespan) != block->RO.bits )
@@ -2453,7 +2449,7 @@ int32_t iguana_bundlesaveHT(struct iguana_info *coin,struct OS_memspace *mem,str
     RAMCHAIN_DESTDECLARE; RAMCHAIN_DECLARE; RAMCHAIN_ZEROES;
     void **ptrs; long *filesizes; uint32_t *ipbits; char fname[1024];
     struct iguana_ramchain *R,*mapchain,*dest,newchain; uint32_t fpipbits; bits256 prevhash2;
-    int32_t i,starti,bROsize,endi,bp_n,numtxids,valid,sigspace,pubkeyspace,numunspents,numspends,numpkinds,numexternaltxids,scriptspace; struct iguana_block *block; long fpos;
+    int32_t i,starti,endi,bp_n,numtxids,valid,sigspace,pubkeyspace,numunspents,numspends,numpkinds,numexternaltxids,scriptspace; struct iguana_block *block; long fpos;
     struct OS_memspace HASHMEM; int32_t err,j,num,hdrsi,bundlei,firsti= 1,retval = -1;
     memset(&HASHMEM,0,sizeof(HASHMEM));
     starti = 0, endi = bp->n - 1;
@@ -2544,7 +2540,6 @@ int32_t iguana_bundlesaveHT(struct iguana_info *coin,struct OS_memspace *mem,str
     dest->H.scriptoffset = 1;
     _iguana_ramchain_setptrs(RAMCHAIN_DESTPTRS,dest->H.data);
     iguana_ramchain_extras(coin,dest,&HASHMEM,0);
-    bROsize = (int32_t)(sizeof(struct iguana_blockRO) + coin->chain->zcash*sizeof(struct iguana_msgblockhdr_zcash));
     for (i=starti; i<=endi; i++)
     {
         if ( coin->active == 0 )
@@ -2563,8 +2558,8 @@ int32_t iguana_bundlesaveHT(struct iguana_info *coin,struct OS_memspace *mem,str
                 iguana_blockunmark(coin,block,bp,i,1);
                 return(-1);
             }
-            destB[i] = block->RO;
-            //memcpy((void *)((long)destB + i*bROsize),&block->RO,bROsize);
+            iguana_blockzcopyRO(coin->chain->zcash,destB,i,&block->RO,0);
+            //destB[i] = block->RO;
         } else printf("error getting block (%d:%d) %p vs %p\n",bp->hdrsi,i,block,bp->blocks[i]);
     }
     dest->H.txidind = dest->H.unspentind = dest->H.spendind = dest->pkind = dest->H.data->firsti;
@@ -2578,7 +2573,7 @@ int32_t iguana_bundlesaveHT(struct iguana_info *coin,struct OS_memspace *mem,str
         {
             iguana_blocksetcounters(coin,block,dest);
             //coin->blocks.RO[bp->bundleheight+bundlei] = block->RO;
-            memcpy((void *)((long)destB + bundlei*bROsize),&block->RO,bROsize);//[bundlei] = block->RO;
+            iguana_blockzcopyRO(coin->chain->zcash,destB,bundlei,&block->RO,0);
             //destB[bundlei] = block->RO;
             //fprintf(stderr,"(%d %d).%d ",R[bundlei].H.data->numtxids,dest->H.txidind,bundlei);
             if ( (err= iguana_ramchain_iterate(coin,dest,&R[bundlei],bp,bundlei)) != 0 )
diff --git a/iguana/iguana_recv.c b/iguana/iguana_recv.c
index 0ddc85e4e..d66b238a1 100755
--- a/iguana/iguana_recv.c
+++ b/iguana/iguana_recv.c
@@ -327,6 +327,7 @@ void iguana_gotblockM(struct iguana_info *coin,struct iguana_peer *addr,struct i
             }
         }
     }
+    origtxdata->zblock.RO.allocsize = sizeof(origtxdata->zblock);
     if ( iguana_blockvalidate(coin,&valid,(struct iguana_block *)&origtxdata->zblock,1) < 0 )
     {
         printf("got block that doesnt validate? %s\n",bits256_str(str,origtxdata->zblock.RO.hash2));
@@ -804,11 +805,6 @@ struct iguana_bundlereq *iguana_recvblockhdrs(struct iguana_info *coin,struct ig
         {
             //fprintf(stderr,"i.%d of %d bundleset\n",i,n);
             bp = 0, bundlei = -1;
-            /*src = (void *)((long)blocks + bsize*i);
-            memset(&zblock,0,sizeof(zblock));
-            zblock.RO.allocsize = sizeof(zblock);
-            iguana_blockconv(coin->chain->zcash,coin->chain->auxpow,(struct iguana_block *)&zblock,src,zblock.RO.hash2,zblock.height);
-            iguana_serialize_block(coin->chain,&zblock.RO.hash2,serialized,(struct iguana_block *)&zblock);*/
             if ( i > 0 && bits256_cmp(prevhash2,zblocks[i].RO.prev_block) == 0 )
             {
                 if ( (bp= iguana_bundleset(coin,&block,&bundlei,(struct iguana_block *)&zblocks[i])) != 0 )
@@ -852,10 +848,6 @@ struct iguana_bundlereq *iguana_recvblockhdrs(struct iguana_info *coin,struct ig
             addr->RThashes[i] = firstbp->hashes[0];
             for (i=1; i<n; i++)
             {
-                /*src = (void *)((long)blocks + bsize*i);
-                memset(&zblock,0,sizeof(zblock));
-                zblock.RO.allocsize = sizeof(zblock);
-                iguana_blockconv(coin->chain->zcash,coin->chain->auxpow,(struct iguana_block *)&zblock,src,zblock.RO.hash2,zblock.height);*/
                 iguana_serialize_block(coin->chain,&addr->RThashes[i],serialized,(struct iguana_block *)&zblocks[i]);
             }
             //memcpy(addr->RThashes,blockhashes,bp->numspec * sizeof(*addr->RThashes));
diff --git a/iguana/iguana_spendvectors.c b/iguana/iguana_spendvectors.c
index 7e081171c..46d1afafa 100755
--- a/iguana/iguana_spendvectors.c
+++ b/iguana/iguana_spendvectors.c
@@ -696,7 +696,7 @@ int32_t iguana_volatilesinit(struct iguana_info *coin)
         //char str[65];
         //printf("set hwmchain.%d <- %s %p\n",bp->bundleheight+bp->n-1,bits256_str(str,bp->hashes[bp->n-1]),block);
         if ( block->height > coin->blocks.hwmchain.height )
-            memcpy(&coin->blocks.hwmchain,block,block->RO.allocsize);
+            iguana_blockzcopy(coin->chain->zcash,(void *)&coin->blocks.hwmchain,block);
     }
     //printf("end volatilesinit\n");
     if ( iguana_fastfindinit(coin) == 0 )//&& coin->PREFETCHLAG >= 0 )
diff --git a/iguana/iguana_tx.c b/iguana/iguana_tx.c
index ae33648ec..7a7490e21 100755
--- a/iguana/iguana_tx.c
+++ b/iguana/iguana_tx.c
@@ -366,7 +366,7 @@ cJSON *iguana_blockjson(struct iguana_info *coin,struct iguana_block *block,int3
     msg.H.merkle_root = block->RO.merkle_root;
     msg.H.timestamp = block->RO.timestamp;
     msg.H.bits = block->RO.bits;
-    if ( block->RO.allocsize == sizeof(*block)+sizeof(*block->zRO) )
+    if ( block->RO.allocsize == sizeof(struct iguana_zblock) )
     {
         msg.zH.bignonce = block->zRO[0].bignonce;
         msg.zH.numelements = ZCASH_SOLUTION_ELEMENTS;