diff --git a/C/bignum.c b/C/bignum.c
index c34d19c1f..2e696df18 100755
--- a/C/bignum.c
+++ b/C/bignum.c
@@ -59,6 +59,28 @@ Yap_MkBigIntTerm(MP_INT *big)
   return AbsAppl(ret);
 }
 
+Term
+Yap_AllocDynamicData(size_t bytes)
+{
+  CACHE_REGS
+  Int nlimbs;
+  MP_INT *dst = (MP_INT *)(H+2);
+  CELL *ret = H;
+
+  nlimbs = ALIGN_YAPTYPE(bytes,CELL)/CellSize;
+  if (nlimbs > (ASP-ret)-1024) {
+    return TermNil;
+  }
+  H[0] = (CELL)FunctorBigInt;
+  H[1] = EXTERNAL_BLOB;
+  dst->_mp_size = 0;
+  dst->_mp_alloc = nlimbs;
+  H = (CELL *)(dst+1)+nlimbs;
+  H[0] = EndSpecials;
+  H++;
+  return AbsAppl(ret);
+}
+
 MP_INT *
 Yap_BigIntOfTerm(Term t)
 {
diff --git a/C/heapgc.c b/C/heapgc.c
index ccae4f8cb..4f48e2c4e 100755
--- a/C/heapgc.c
+++ b/C/heapgc.c
@@ -1325,7 +1325,7 @@ mark_variable(CELL_PTR current USES_REGS)
 	  sz++;
 #if DEBUG
 	  if (next[sz] != EndSpecials)  {
-	    fprintf(stderr,"[ Error: could not find EndSpecials at blob %p type %lx ]\n", next, next[1]);
+	    fprintf(stderr,"[ Error: could not find EndSpecials at blob %p type " UInt_FORMAT " ]\n", next, next[1]);
 	}
 #endif
 	  MARK(next+sz);
@@ -1904,11 +1904,11 @@ mark_choicepoints(register choiceptr gc_B, tr_fr_ptr saved_TR, int very_verbose
       PredEntry *pe = Yap_PredForChoicePt(gc_B);
 #if defined(ANALYST) || defined(DEBUG)
       if (pe == NULL) {
-	fprintf(GLOBAL_stderr,"%%       marked %ld (%s)\n", LOCAL_total_marked, Yap_op_names[opnum]);
+	fprintf(GLOBAL_stderr,"%%       marked  " UInt_FORMAT " (%s)\n", LOCAL_total_marked, Yap_op_names[opnum]);
       } else if (pe->ArityOfPE) {
-	fprintf(GLOBAL_stderr,"%%       %s/%d marked %ld (%s)\n", RepAtom(NameOfFunctor(pe->FunctorOfPred))->StrOfAE, pe->ArityOfPE, LOCAL_total_marked, Yap_op_names[opnum]);
+	fprintf(GLOBAL_stderr,"%%       %s/%d marked  " UInt_FORMAT " (%s)\n", RepAtom(NameOfFunctor(pe->FunctorOfPred))->StrOfAE, pe->ArityOfPE, LOCAL_total_marked, Yap_op_names[opnum]);
       } else {
-	fprintf(GLOBAL_stderr,"%%       %s marked %ld (%s)\n", RepAtom((Atom)(pe->FunctorOfPred))->StrOfAE, LOCAL_total_marked, Yap_op_names[opnum]);
+	fprintf(GLOBAL_stderr,"%%       %s marked  " UInt_FORMAT " (%s)\n", RepAtom((Atom)(pe->FunctorOfPred))->StrOfAE, LOCAL_total_marked, Yap_op_names[opnum]);
       }
 #else
       if (pe == NULL) {
diff --git a/H/TermExt.h b/H/TermExt.h
index 61c617e6b..d090fa0ea 100755
--- a/H/TermExt.h
+++ b/H/TermExt.h
@@ -86,7 +86,7 @@ typedef enum
     CLAUSE_LIST =  0x40,
     BLOB_STRING =  0x80, /* SWI style strings */
     BLOB_WIDE_STRING =  0x81, /* SWI style strings */
-    EXTERNAL_BLOB =  0x100 /* for SWI emulation */
+    EXTERNAL_BLOB =  0x100 /* generic data */
   } 
 big_blob_type;
 
@@ -438,6 +438,25 @@ IsLargeNumTerm (Term t)
 		    && (FunctorOfTerm (t) >= FunctorLongInt)));
 }
 
+inline EXTERN int IsExternalBlobTerm (Term);
+
+inline EXTERN int
+IsExternalBlobTerm (Term t)
+{
+  return (int) (IsApplTerm (t) &&
+		FunctorOfTerm (t) == FunctorBigInt &&
+		RepAppl(t)[1] == EXTERNAL_BLOB);
+}
+
+inline EXTERN void *ExternalBlobFromTerm (Term);
+
+inline EXTERN void *
+ExternalBlobFromTerm (Term t)
+{
+  MP_INT *base = (MP_INT *)(RepAppl(t)+2);
+  return (void *) (base+1);
+}
+
 
 
 
diff --git a/H/Yapproto.h b/H/Yapproto.h
index 0c8be2542..06f855e01 100755
--- a/H/Yapproto.h
+++ b/H/Yapproto.h
@@ -120,6 +120,7 @@ int    STD_PROTO(Yap_IsStringTerm, (Term));
 int    STD_PROTO(Yap_IsWideStringTerm, (Term));
 Term   STD_PROTO(Yap_RatTermToApplTerm, (Term));
 void   STD_PROTO(Yap_InitBigNums, (void));
+Term   STD_PROTO(Yap_AllocDynamicData, (size_t));
 
 /* c_interface.c */
 Int    STD_PROTO(YAP_Execute,(struct pred_entry *, CPredicate));