diff --git a/C/agc.c b/C/agc.c
index a8fe53696..0335dcf76 100644
--- a/C/agc.c
+++ b/C/agc.c
@@ -329,6 +329,29 @@ mark_global_cell(CELL *pt)
 	Int sz = 3 +
 	  (sizeof(MP_INT)+
 	   (((MP_INT *)(pt+2))->_mp_alloc*sizeof(mp_limb_t)))/sizeof(CELL);
+	Opaque_CallOnGCMark f;
+	Opaque_CallOnGCRellocate f2;
+
+	if ( (f = Yap_blob_gc_mark_handler(reg)) ) {
+	  CELL ar[256];
+	  Int i,n = (f)(Yap_BlobTag(reg), Yap_BlobInfo(reg), ar, 256);
+	  if (n < 0) {
+	    Yap_Error(OUT_OF_HEAP_ERROR,TermNil,"not enough space for slot internal variables in agc");
+	      }
+	  for (i = 0; i< n; i++) {
+	    CELL *pt = ar+i;
+	    CELL reg = *pt;
+	    if (!IsVarTerm(reg) && IsAtomTerm(reg)) {
+	      *pt = AtomTermAdjust(reg);
+	    }
+	  }
+	  if ( (f2 = Yap_blob_gc_rellocate_handler(reg)) < 0 ) {
+	    int out = (f2)(Yap_BlobTag(reg), Yap_BlobInfo(reg), ar, n);
+	    if (out < 0)
+	      Yap_Error(OUT_OF_HEAP_ERROR,TermNil,"bad restore of slot internal variables in agc");
+	  }
+	}
+
 	return pt + sz;
       }
     case (CELL)FunctorLongInt:
diff --git a/C/grow.c b/C/grow.c
index da18c3533..be6fef28a 100644
--- a/C/grow.c
+++ b/C/grow.c
@@ -572,16 +572,48 @@ AdjustGlobal(long sz, int thread_copying USES_REGS)
 	  pt += 2;
 #endif
 	  break;
-#if USE_GMP
 	case (CELL)FunctorBigInt:
 	  {
 	    Int sz = 2+
 	      (sizeof(MP_INT)+
 	       (((MP_INT *)(pt+2))->_mp_alloc*sizeof(mp_limb_t)))/CellSize;
+	    Opaque_CallOnGCMark f;
+	    Opaque_CallOnGCRellocate f2;
+
+	    if ( (f = Yap_blob_gc_mark_handler(reg)) ) {
+	      CELL ar[256];
+	      Int i,n = (f)(Yap_BlobTag(reg), Yap_BlobInfo(reg), ar, 256);
+	      if (n < 0) {
+		Yap_Error(OUT_OF_HEAP_ERROR,TermNil,"not enough space for slot internal variables");
+	      }
+	      for (i = 0; i< n; i++) {
+		CELL *pt = ar+i;
+		CELL reg = *pt;
+		if (IsVarTerm(reg)) {
+		  if (IsOldGlobal(reg))
+		    *pt = GlobalAdjust(reg);
+		  else if (IsOldLocal(reg))
+		    *pt = LocalAdjust(reg);
+#ifdef MULTI_ASSIGNMENT_VARIABLES
+		  else if (IsOldTrail(reg))
+		    *pt = TrailAdjust(reg);
+#endif
+		} else if (IsApplTerm(reg))
+		  *pt = AdjustAppl(reg PASS_REGS);
+		else if (IsPairTerm(reg))
+		  *pt = AdjustPair(reg PASS_REGS);
+		else if (IsAtomTerm(reg))
+		  *pt = AtomTermAdjust(reg);
+	      }
+	      if ( (f2 = Yap_blob_gc_rellocate_handler(reg)) < 0 ) {
+		int out = (f2)(Yap_BlobTag(reg), Yap_BlobInfo(reg), ar, n);
+		if (out < 0)
+		Yap_Error(OUT_OF_HEAP_ERROR,TermNil,"bad restore of slot internal variables");
+	      }
+	    }
 	    pt += sz;
 	  }
 	  break;
-#endif
 	case (CELL)0L:
 	  break;
 	case (CELL)FunctorLongInt: